## Q&A - PSLE Math

### Re: Q&A - PSLE Math

pls help

I have some red and blue counters in a box, I add in 20 red counters, the ratio of my red counters to my blue counters becomes 2:3. Then I add in another 60 blue counters, the ratio of my red counters to my blue counters becomes 1:3, How may counters do I have in the box at first?

Tks

I have some red and blue counters in a box, I add in 20 red counters, the ratio of my red counters to my blue counters becomes 2:3. Then I add in another 60 blue counters, the ratio of my red counters to my blue counters becomes 1:3, How may counters do I have in the box at first?

Tks

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

### Re: Q&A - PSLE Math

Let the number of red and blue counters be r and b respectively.TeacherLinus wrote:waterfall wrote:pls help

I have some red and blue counters in a box, I add in 20 red counters, the ratio of my red counters to my blue counters becomes 2:3. Then I add in another 60 blue counters, the ratio of my red counters to my blue counters becomes 1:3, How may counters do I have in the box at first?

Tks

**:**

*Red*

*Blue*r + 20 : b

2 : 3

r + 20 : b + 60

1 : 3

3(r + 20) = 2b

3(r + 20) = b + 60

2b = b + 60

b = 60

3r + 60 = 120

r = 20

60 + 20 = 80

Ans : 80 counters.

### Re: Q&A - PSLE Math

Hi all,

Please help me to explain these 2 sentences meant.

1. A watch cost $230 at store M and 15% less in store Y. Find the original price of the watch in store L.

2. Store X sells a bag at $600 which is 25% less than the price of the same bag in store Y . Find the bag in store Y.

Thank..all

Please help me to explain these 2 sentences meant.

1. A watch cost $230 at store M and 15% less in store Y. Find the original price of the watch in store L.

2. Store X sells a bag at $600 which is 25% less than the price of the same bag in store Y . Find the bag in store Y.

Thank..all

- speedmaths.com
- BrownBelt
**Posts:**559**Joined:**Mon Oct 12,**Total Likes:**3

### Re: Q&A - PSLE Math

Hi,Daddy wrote:Hi all,

Please help me to explain these 2 sentences meant.

1. A watch cost $230 at store M and 15% less in store Y. Find the original price of the watch in store L.

2. Store X sells a bag at $600 which is 25% less than the price of the same bag in store Y . Find the bag in store Y.

Thank..all

Likely mean that some words are missing.

Cheers.

SpeedMaths

.

- speedmaths.com
- BrownBelt
**Posts:**559**Joined:**Mon Oct 12,**Total Likes:**3

### Re: Q&A - PSLE Math

Q2.speedmaths.com wrote:Hi,Daddy wrote:Hi all,

Please help me to explain these 2 sentences meant.

1. A watch cost $230 at store M and 15% less in store Y. Find the original price of the watch in store L.

2. Store X sells a bag at $600 which is 25% less than the price of the same bag in store Y . Find the bag in store Y.

Thank..all

Likely mean that some words are missing.

Cheers.

SpeedMaths

.

"Find the price of the bag in store Y."

Cheers.

SpeedMaths

.

### Re: Q&A - PSLE Math

Sorry.

typo error

Q1. Find store Y instead of store L.

Q2. Find the price of the bag in store Y .

sorry...Thank .

typo error

Q1. Find store Y instead of store L.

Q2. Find the price of the bag in store Y .

sorry...Thank .

### Re: Q&A - PSLE Math

tksalfretztay wrote:Let the number of red and blue counters be r and b respectively.TeacherLinus wrote:waterfall wrote:pls help

I have some red and blue counters in a box, I add in 20 red counters, the ratio of my red counters to my blue counters becomes 2:3. Then I add in another 60 blue counters, the ratio of my red counters to my blue counters becomes 1:3, How may counters do I have in the box at first?

Tks

:RedBlue

r + 20 : b

2 : 3

r + 20 : b + 60

1 : 3

3(r + 20) = 2b

3(r + 20) = b + 60

2b = b + 60

b = 60

3r + 60 = 120

r = 20

60 + 20 = 80

Ans : 80 counters.

### Re: Q&A - PSLE Math

Let me try using another way.waterfall wrote:pls help

I have some red and blue counters in a box, I add in 20 red counters, the ratio of my red counters to my blue counters becomes 2:3. Then I add in another 60 blue counters, the ratio of my red counters to my blue counters becomes 1:3, How may counters do I have in the box at first?

Tks

R20 : B ->2u:3u

R20:B60 -> 1:3

We can get common unit via making R20 the same.

R20:B60 -> 2u:6u

Difference between B and B60 -> 6u-3u = 60

u=20

total of R20:B-> 5u-> 100.

In the beginning is 100-20 = 80 counters.

### Re: Q&A - PSLE Math

thanks!Ender wrote:Let me try using another way.

I have some red and blue counters in a box, I add in 20 red counters, the ratio of my red counters to my blue counters becomes 2:3. Then I add in another 60 blue counters, the ratio of my red counters to my blue counters becomes 1:3, How may counters do I have in the box at first?

Tks

R20 : B ->2u:3u

R20:B60 -> 1:3

We can get common unit via making R20 the same.

R20:B60 -> 2u:6u

Difference between B and B60 -> 6u-3u = 60

u=20

total of R20:B-> 5u-> 100.

In the beginning is 100-20 = 80 counters.