You are given a math word problem and you are supposed to apply multiple mathematical operators like addition, subtraction, multiplication, or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

the ice rink has 85 pairs of skates to rent . 18 people rented skates when the ice rink opened . 25 more people rented skates during the first hour . how many pairs of skates are left ?
42