Free ACT Practice Question

Chad starts reading a book having 120 pages and wants to finish reading it over a period of 10 days. Initially, for the first $x$ days, he reads 2 pages every day; and for the next $y$ days, he reads half a page more per day than what he was reading previously. If, for the last few days, he reads more than 15 pages per day, which of the following gives the correct relation between $x$ and $y$?