Answer:
7/8
Explanation:
If you turn 1 3/4 back into a simplified fraction it is 7/4. But the denominators need to be the same, so multiply the bottom number 2 and the top number by 2. That gives you 14/8. If she used 7/8 of it, then you just do 14/8 - 7/8 which gives you 7/8.