PSLE
Four girls, Cathy, Gwen, Winnie and Dana raised money for a charity. Cathy and Gwen raised a total of $181. Together, Gwen, Winnie and Dana raised a total of $311. The total amount of money raised by all 4 girls is 5 times the amount that Gwen raised. How much money did Gwen raise?
Amount that Gwen and Cathy raised = $181
Amount that Gwen, Winnie and Dana raised = $311

Gwen is the repeated identity.

Gwen + Cathy = 181 --- (1)
Gwen + Winnie + Dana = 311 --- (2)

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

(1) + (2)
(Gwen + Cathy) + (Gwen + Winnie + Dana) = 181 + 311
Gwen + 4 girls = 492
1 u + 5 u = 492
6 u = 492

1 u = 492 ÷ 6 = 82

Amount that Gwen raised
= 1 u
= $82

Answer(s): $82