Answer:
$100
Explanation:
Step 1, setting up an equation:
If Marina spent
of her money, she has
of her money remaining. We also are given that she has $80 left. We can set her initial total amount of money as x to solve this problem:

Step 2, solving for x:

We have set x as her original amount of money, so we have the answer!
Marina originally had
dollars.
I hope this helps! Let me know if you have any questions :)