A Football team gained 7 yards on the first down, lost 15 yards on the second down, and gained 12 yards on the third down. How many yards does it need to gain on the fourth down to have a 10 yard gain?

It gained 7 on the first down, + 7

it lost 15 on second down, - 15

gained 12 on third down, + 12

+7 - 15 + 12 = 4

thus far is ahead with 4 yards, how many more to get to 10? well, 10 - 4? surely you know that.

It needs to gain 4 more yards.