Irene and Shiyun have $165. Lucy and Irene have $201. The ratio of Shiyun to Lucy is 4 : 7. How much does Irene have?
Amount that Shiyun has = 4 u
Amount that Lucy has = 7 u
The amount that Irene has is the repeated identity.
Irene + 4 u = 165 --- (1)
Irene + 7 u = 201 --- (2)
(2) - (1)
7 u - 4 u = 201 - 165
3 u = 36
1 u = 36 ÷ 3 = 12
From (1):
Irene + 4 u = 165
Irene + 4 x 12 = 165
Irene + 48 = 165
Amount that Irene has
= 165 - 48
= $117
Answer(s): $117
