Answer:
She started with 8.90
Step-by-step explanation:
Let m = money
She spent 1/2 on a book
m - 1/2 m
This is what she has left after buying her book
Now she buys a pen at 1.25
m-1/2m - 1.25
This is how much she has left after buying the pen
The problem states that she has 3.20 left
3.20 = m-1/2m - 1.25
Combine like terms
3.20 = 1/2 m - 1.25
Add 1.25 to each side
3.2+1.25 = 1/2m -1.25 +1.25
4.45 = 1/2m
Multiply by 2
2*4.45 = 1/2m*2
8.90 = m
She started with 8.90
