PSLE
Four girls, Irene, Rachel, Erika and Kathy raised money for a charity. Irene and Rachel raised a total of $131. Together, Rachel, Erika and Kathy raised a total of $85. The total amount of money raised by all 4 girls is 5 times the amount that Rachel raised. How much money did Irene raise?
Amount that Rachel and Irene raised = $131
Amount that Rachel, Erika and Kathy raised = $85

Rachel is the repeated identity.

Rachel + Irene = 131 --- (1)
Rachel + Erika + Kathy = 85 --- (2)

Amount that Rachel raised = 1 u
Amount that 4 girls raised = 5 u

(1) + (2)
(Rachel + Irene) + (Rachel + Erika + Kathy) = 131 + 85
Rachel + 4 girls = 216
1 u + 5 u = 216
6 u = 216

1 u = 216 ÷ 6 = 36

Amount that Irene raised
= 131 - 1 u
= 131 - 36
= $95

Answer(s): $95