When subtracting like fractions, what happens to the numerator and the denominator?

Ineed to learn how to solve this problem

Write the product as a trinomial. (x + 2)(x + 3) x2 + 5x + 6 x2 + 6x + 6 x2 + 6x + 5 x2 + 5

Aball is thrown from a height of 139 feet with an initial downward velocity of 15 ft/s. the ball's height h (in feet) after t seconds is given by the following. h=139-15t-16t^2 how long after the ball is thrown does it hit the ground? round your answer(s) to the nearest hundredth. (if there is more than one answer, use the "or" button.) t =