Answer:
A water bottle
Step-by-step explanation:
It's a water bottle because you cannot measure volume with a dollr bill or postage stamp.
12x - 6y + 9z - (-x - 3z + 6y) = 12x - 6y + 9z + x + 3z - 6y = 13x - 12y + 12z
I am to believe that his score was 70.
since mike scored 15 less than 85 i had suspected it was 70