PSLE
Four girls, Penelope, Rachel, Abi and Usha raised money for a charity. Penelope and Rachel raised a total of $86. Together, Rachel, Abi and Usha raised a total of $190. The total amount of money raised by all 4 girls is 3 times the amount that Rachel raised. How much money did Penelope raise?
Amount that Rachel and Penelope raised = $86
Amount that Rachel, Abi and Usha raised = $190

Rachel is the repeated identity.

Rachel + Penelope = 86 --- (1)
Rachel + Abi + Usha = 190 --- (2)

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

(1) + (2)
(Rachel + Penelope) + (Rachel + Abi + Usha) = 86 + 190
Rachel + 4 girls = 276
1 u + 3 u = 276
4 u = 276

1 u = 276 ÷ 4 = 69

Amount that Penelope raised
= 86 - 1 u
= 86 - 69
= $17

Answer(s): $17