Erika and Natalie have $151. Zoe and Erika have $171. The ratio of Natalie to Zoe is 1 : 2. How much does Erika have?
Amount that Natalie has = 1 u
Amount that Zoe has = 2 u
The amount that Erika has is the repeated identity.
Erika + 1 u = 151 --- (1)
Erika + 2 u = 171 --- (2)
(2) - (1)
2 u - 1 u = 171 - 151
1 u = 20
From (1):
Erika + 1 u = 151
Erika + 1 x 20 = 151
Erika + 20 = 151
Amount that Erika has
= 151 - 20
= $131
Answer(s): $131
