# Question

16 : 9 : 7.     1/8 of the \$2 gift packs and 34 of the \$5 gift packs were sold.  The remaining gift packs were worth \$1975.  How many of the \$10 gift packs were there?

At first

Qty:

\$2 -> 16u

\$5 -> 9u

\$10 -> 7u

1/8 of \$2-pack, and 34 of \$5-pack were sold

Qty:

\$2 -> 14u

\$5 -> 9u – 34

\$10 -> 7u

Pack Value:

\$2 -> 14u x 2 = 28u

\$5 -> (9u – 34) x 5 = 45u – 170

\$10 -> 7u x 10 = 70u

28u + 45u – 170 + 70u = 1975

143u = 2145

1u = 15

There were 7 x 15 = 105 \$10 gift packs

Thank you for your solutions, BigDevil, Ender and SAHMom.
Really appreciate it.

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Hi,

We may use a table to list it.

 \$2 \$5 \$10 Total Before 16u 9u 7u After 14u 9u – 34 7u Each \$2 \$5 \$10 Amount 28u 45-170 70u 143u-170

143u – 170 = 1975
143u = 1975 + 170
143u = 2145
1u = 15

7u = 7 × 15 = 105 packs

I found that using table, some kids are able to understand the question better. Not all kids understand the model drawing.

However, I do not understand why primary teacher use arrow instead of equal sign.

143u — > 1975 + 170

Then in secondary school, the teachers taught the student to use equal sign in equation.

143u = 1975 + 179

Why can’t they do in a consistent way?

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Thank you for your working, Khong Pek Mao.

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When I first started ‘re-learning’ primary school math in order to coach my son. I am also baffle with the arrows in place of ‘=’.

Now have gotten use to seeing it, even though I don’t use it in my solution.

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16u of \$2 gift pack. If 1/8 are sold, 7/8 are left which is, => 14u

34 of \$5 pack is worth 34 X 5 = \$170
Left over value of \$5 pack = 9u(\$5) -170

Total leftover value is,
14u (\$2) + 9u (\$5) – \$170 + 7u(\$10) = \$1975
28u + 45u + 70u – 170 = 1975
143u = 2145
u = 15

\$10 pack = 7u = 105 packs. ##

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Try table for summarising info (view landscape):