Answer:
x - y + y =x is your answer hope it helps
Step-by-step explanation:
like terms can be add or subtract
x
because it form + and - it has to equal 0 . so it is toally x.
Subtract original amount from new amount:
84 - 39 = 45
He bought 45 books.
85miles¯\_(ツ)_/¯
