PSLE
Four girls, Irene, Zara, Esther and Risa raised money for a charity. Irene and Zara raised a total of $136. Together, Zara, Esther and Risa raised a total of $199. The total amount of money raised by all 4 girls is 4 times the amount that Zara raised. How much money did Zara raise?
Amount that Zara and Irene raised = $136
Amount that Zara, Esther and Risa raised = $199

Zara is the repeated identity.

Zara + Irene = 136 --- (1)
Zara + Esther + Risa = 199 --- (2)

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

(1) + (2)
(Zara + Irene) + (Zara + Esther + Risa) = 136 + 199
Zara + 4 girls = 335
1 u + 4 u = 335
5 u = 335

1 u = 335 ÷ 5 = 67

Amount that Zara raised
= 1 u
= $67

Answer(s): $67