Acar company tested a sports car on a road with different inclines. the test driver tested the car by driving a distance of x miles on a flat road, (x2 + 3) miles downhill, and (x - 7) miles uphill. which simplified expression is equivalent to the total distance, in miles, for which the car was tested?

3x2 _ 4

3x2 + 10

x2 + 2x - 4

x2 + 2x + 10

i suck at word problems