PSLE
Four girls, Olivia, Cathy, Fanny and Yen raised money for a charity. Olivia and Cathy raised a total of $156. Together, Cathy, Fanny and Yen raised a total of $199. The total amount of money raised by all 4 girls is 4 times the amount that Cathy raised. How much money did Fanny and Yen raise?
Amount that Cathy and Olivia raised = $156
Amount that Cathy, Fanny and Yen raised = $199

Cathy is the repeated identity.

Cathy + Olivia = 156 --- (1)
Cathy + Fanny + Yen = 199 --- (2)

Amount that Cathy raised = 1 u
Amount that 4 girls raised = 4 u

(1) + (2)
(Cathy + Olivia) + (Cathy + Fanny + Yen) = 156 + 199
Cathy + 4 girls = 355
1 u + 4 u = 355
5 u = 355

1 u = 355 ÷ 5 = 71

Total amount that Fanny and Yen raised
= 199 - 1 u
= 199 - 71
= $128

Answer(s): $128