Gabby and Xuan have $309. Betty and Gabby have $373. The ratio of Xuan to Betty is 3 : 7. How much does Gabby have?
Amount that Xuan has = 3 u
Amount that Betty has = 7 u
The amount that Gabby has is the repeated identity.
Gabby + 3 u = 309 --- (1)
Gabby + 7 u = 373 --- (2)
(2) - (1)
7 u - 3 u = 373 - 309
4 u = 64
1 u = 64 ÷ 4 = 16
From (1):
Gabby + 3 u = 309
Gabby + 3 x 16 = 309
Gabby + 48 = 309
Amount that Gabby has
= 309 - 48
= $261
Answer(s): $261
