PSLE
Billy and Bryan have the same total number of coins. Billy has a number of fifty-cent coins and 37 ten-cent coins. The total mass of his coins is 0.665 kg. Bryan has a number of fifty-cent coins and 87 ten-cent coins.

1. Who has less money in coins? How much less? Give your answers in this format. (Eg Adam, $12)
2. Each fifty-cent coin is 2.8 g heavier than each ten-cent coin. What is the total mass of Bryan's coins in kg?

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

Difference in the number of ten-cent coins.
= 87 - 37
= 50

Difference in the value of 1 ten-cent coin and 1 fifty-cent coin
= 50 - 10
= 40¢

Amount that Bryan had less than Billy
= 50 x 40
= 2000¢
= $20

(b)
Difference in the mass between 50 ten-cent coins and 50 fifty-cent coins
= 50 x 2.8
= 140 g
= 0.14 kg

Total mass of Bryan's coins
= 0.665 - 0.14
= 0.525 kg

Answer(s): (a) Billy, $20; (b) 0.525 kg