PSLE
Four girls, Esther, Hilda, Jen and Gem raised money for a charity. Esther and Hilda raised a total of $85. Together, Hilda, Jen and Gem raised a total of $105. The total amount of money raised by all 4 girls is 4 times the amount that Hilda raised. How much money did Esther raise?
Amount that Hilda and Esther raised = $85
Amount that Hilda, Jen and Gem raised = $105

Hilda is the repeated identity.

Hilda + Esther = 85 --- (1)
Hilda + Jen + Gem = 105 --- (2)

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

(1) + (2)
(Hilda + Esther) + (Hilda + Jen + Gem) = 85 + 105
Hilda + 4 girls = 190
1 u + 4 u = 190
5 u = 190

1 u = 190 ÷ 5 = 38

Amount that Esther raised
= 85 - 1 u
= 85 - 38
= $47

Answer(s): $47