PSLE
Four girls, Natalie, Roshel, Cindy and Nora raised money for a charity. Natalie and Roshel raised a total of $169. Together, Roshel, Cindy and Nora raised a total of $191. The total amount of money raised by all 4 girls is 3 times the amount that Roshel raised. How much money did Roshel raise?
Amount that Roshel and Natalie raised = $169
Amount that Roshel, Cindy and Nora raised = $191

Roshel is the repeated identity.

Roshel + Natalie = 169 --- (1)
Roshel + Cindy + Nora = 191 --- (2)

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

(1) + (2)
(Roshel + Natalie) + (Roshel + Cindy + Nora) = 169 + 191
Roshel + 4 girls = 360
1 u + 3 u = 360
4 u = 360

1 u = 360 ÷ 4 = 90

Amount that Roshel raised
= 1 u
= $90

Answer(s): $90