PSLE
Four girls, Cindy, Dana, Tammy and Zara raised money for a charity. Cindy and Dana raised a total of $102. Together, Dana, Tammy and Zara raised a total of $198. The total amount of money raised by all 4 girls is 3 times the amount that Dana raised. How much money did Tammy and Zara raise?
Amount that Dana and Cindy raised = $102
Amount that Dana, Tammy and Zara raised = $198

Dana is the repeated identity.

Dana + Cindy = 102 --- (1)
Dana + Tammy + Zara = 198 --- (2)

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

(1) + (2)
(Dana + Cindy) + (Dana + Tammy + Zara) = 102 + 198
Dana + 4 girls = 300
1 u + 3 u = 300
4 u = 300

1 u = 300 ÷ 4 = 75

Total amount that Tammy and Zara raised
= 198 - 1 u
= 198 - 75
= $123

Answer(s): $123