Set up givens and equations

- Let the cost of the dog be d
- Let the cost of the cat be c

- c + d = 100
- d = c + 90

c + c + 90 = 100

Using our math engine, we see that:

c =

**5**

Substitute c = 5 into equation (2) above:

d = 5 + 90

d =

**95**

- Thread starter math_celebrity
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