------------20-cents----50-centsBunny27 wrote:Hi, pls help on this question.

Miss Phua saved some 20-cent coins and 50-cent coins in the ratio of 3:4 in a box. She then decided to replace 1/3 of the 20-cent coins with the same number of 50-cent coins.The value of the amount she saved increased by $4.50. How much money was there in the box at first?

Thank you!

Before-------3u----------4u

After --------2u----------5u (because 1/3(3u)->u)

remove

1/3 20ct

and add

same number of 50 cents

50u-20u->450

30u->450

u->15

**Money in box at first : 3(15)(0.20)+4(15)(0.50) = 9+30 = $39**