PSLE
Four girls, Xandra, Nora, Shannon and Tina raised money for a charity. Xandra and Nora raised a total of $129. Together, Nora, Shannon and Tina raised a total of $369. The total amount of money raised by all 4 girls is 5 times the amount that Nora raised. How much money did Xandra raise?
Amount that Nora and Xandra raised = $129
Amount that Nora, Shannon and Tina raised = $369

Nora is the repeated identity.

Nora + Xandra = 129 --- (1)
Nora + Shannon + Tina = 369 --- (2)

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

(1) + (2)
(Nora + Xandra) + (Nora + Shannon + Tina) = 129 + 369
Nora + 4 girls = 498
1 u + 5 u = 498
6 u = 498

1 u = 498 ÷ 6 = 83

Amount that Xandra raised
= 129 - 1 u
= 129 - 83
= $46

Answer(s): $46