PSLE
Rael and David have the same total number of coins. Rael has a number of twenty-cent coins and 45 ten-cent coins. The total mass of his coins is 0.882 kg. David has a number of twenty-cent coins and 75 ten-cent coins.

1. Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
2. Each twenty-cent coin is 1.2 g heavier than each ten-cent coin. What is the total mass of David's coins in kg?

(a)
Since Rael has less ten-cent coins than David but both had the same number of coins, Rael had more money.

Both boys have the same number of coins. Since Rael has less ten-cent coins than David, it means that Rael has more twenty-cent coins than David. So Rael has more money.

Difference in the number of ten-cent coins.
= 75 - 45
= 30

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

Amount that Rael had more than David
= 30 x 10
= 300¢
= $3

(b)
Difference in the mass between 30 ten-cent coins and 30 twenty-cent coins
= 30 x 1.2
= 36 g
= 0.036 kg

Total mass of David's coins
= 0.882 - 0.036
= 0.846 kg

Answer(s): (a) Rael, $3; (b) 0.846 kg