Answer:
The answer is $10... If I'm doing the math correctly.
Explanation:
Think of $100 as $1, if you spent 3/4 of a dollar you basically spent 75 cents. Since it's $100 you would've spent $75, so that's your new total.
Now 1/5 of 75 is 15, so there for you spent an extra $15, so you only have $10 left.