PSLE
Four girls, Tammy, Fanny, Diana and Xuan raised money for a charity. Tammy and Fanny raised a total of $91. Together, Fanny, Diana and Xuan raised a total of $205. The total amount of money raised by all 4 girls is 3 times the amount that Fanny raised. How much money did Fanny raise?
Amount that Fanny and Tammy raised = $91
Amount that Fanny, Diana and Xuan raised = $205

Fanny is the repeated identity.

Fanny + Tammy = 91 --- (1)
Fanny + Diana + Xuan = 205 --- (2)

Amount that Fanny raised = 1 u
Amount that 4 girls raised = 3 u

(1) + (2)
(Fanny + Tammy) + (Fanny + Diana + Xuan) = 91 + 205
Fanny + 4 girls = 296
1 u + 3 u = 296
4 u = 296

1 u = 296 ÷ 4 = 74

Amount that Fanny raised
= 1 u
= $74

Answer(s): $74