Answer:
87 toothpicks
Explanation:
If Marie has 231 toothpicks in one box and 175 in the other, you can add them together which would get:
231
+ 175
_________
406
If Marie uses up 319 toothpicks, then you would have to subtract the 319 toothpicks from the 406 toothpicks in order to see how much is left:
406
- 319
________
87
which would leave you with 87 toothpicks left!