PSLE
Four girls, Lucy, Marion, Winnie and Usha raised money for a charity. Lucy and Marion raised a total of $116. Together, Marion, Winnie and Usha raised a total of $219. The total amount of money raised by all 4 girls is 4 times the amount that Marion raised. How much money did Lucy raise?
Amount that Marion and Lucy raised = $116
Amount that Marion, Winnie and Usha raised = $219

Marion is the repeated identity.

Marion + Lucy = 116 --- (1)
Marion + Winnie + Usha = 219 --- (2)

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

(1) + (2)
(Marion + Lucy) + (Marion + Winnie + Usha) = 116 + 219
Marion + 4 girls = 335
1 u + 4 u = 335
5 u = 335

1 u = 335 ÷ 5 = 67

Amount that Lucy raised
= 116 - 1 u
= 116 - 67
= $49

Answer(s): $49