PSLE
Four girls, Kathy, Rachel, Cindy and Mary raised money for a charity. Kathy and Rachel raised a total of $145. Together, Rachel, Cindy and Mary raised a total of $359. The total amount of money raised by all 4 girls is 5 times the amount that Rachel raised. How much money did Kathy raise?
Amount that Rachel and Kathy raised = $145
Amount that Rachel, Cindy and Mary raised = $359

Rachel is the repeated identity.

Rachel + Kathy = 145 --- (1)
Rachel + Cindy + Mary = 359 --- (2)

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

(1) + (2)
(Rachel + Kathy) + (Rachel + Cindy + Mary) = 145 + 359
Rachel + 4 girls = 504
1 u + 5 u = 504
6 u = 504

1 u = 504 ÷ 6 = 84

Amount that Kathy raised
= 145 - 1 u
= 145 - 84
= $61

Answer(s): $61