PSLE
Four girls, Zara, Tina, Mary and Ivory raised money for a charity. Zara and Tina raised a total of $129. Together, Tina, Mary and Ivory raised a total of $135. The total amount of money raised by all 4 girls is 5 times the amount that Tina raised. How much money did Zara raise?
Amount that Tina and Zara raised = $129
Amount that Tina, Mary and Ivory raised = $135

Tina is the repeated identity.

Tina + Zara = 129 --- (1)
Tina + Mary + Ivory = 135 --- (2)

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

(1) + (2)
(Tina + Zara) + (Tina + Mary + Ivory) = 129 + 135
Tina + 4 girls = 264
1 u + 5 u = 264
6 u = 264

1 u = 264 ÷ 6 = 44

Amount that Zara raised
= 129 - 1 u
= 129 - 44
= $85

Answer(s): $85