One spring, Mr. Gambrill felt as if he needed to mow his lawn particularly often. So after a mowing, he measured the height of his grass. He continued to measure it each day until the next mowing. The equation below represents the relationship between time, x, in days and height of the grass, y, in centimeters. What was the rate of change for the growth of Mr. Grambrill's grass?

y = 6 + 1.5x (y equals six plus one point five)

the answer is one of these: how do u solve it plz =]

1.5 cm/day

4.5 cm/day

6 cm/day

10 points fo best answer