Marty's plant measured 7.35 inches at the beginning of the summer. It measured 8.125 inches at the end of summer. How much did Marty's plant grow over the summer?

We need to find the distance between 8.125 and 7.35 to find how much the plant grew over the summer. We can subtract 7.35 from 8.125 to find this.
8.125 - 7.35 = 0.775
So Marty's plant grew 0.775 inches over the summer.