PSLE
Owen and Tommy have the same total number of coins. Owen has a number of twenty-cent coins and 30 ten-cent coins. The total mass of his coins is 0.76 kg. Tommy has a number of twenty-cent coins and 50 ten-cent coins.

1. Who has less money in coins? How much less? Give your answers in this format. (Eg Adam, $12)
2. Each twenty-cent coin is 2.5 g heavier than each ten-cent coin. What is the total mass of Tommy's coins in kg?

(a)
Both boys have the same number of coins. Since Tommy has more ten-cent coins than Owen, it means that Tommy has less twenty-cent coins than Owen.  So Tommy has less money.

Difference in the number of ten-cent coins.
= 50 - 30
= 20

Difference in the value of 1 ten-cent coin and 1 twenty-cent coin
= 20 - 10
= 10¢

Amount that Tommy had less than Owen
= 20 x 10
= 200¢
= $2

(b)
Difference in the mass between 20 ten-cent coins and 20 twenty-cent coins
= 20 x 2.5
= 50 g
= 0.05 kg

Total mass of Tommy's coins
= 0.76 - 0.05
= 0.71 kg

Answer(s): (a) Owen, $2; (b) 0.71 kg