13. A ball is kicked straight up into the air. The height of the ball in feet is given by the expression -16t + 12t + 4, where t is time in seconds. Factor the expression. Then find the height of the ball after 1 second. 14. A rectangular painting has an area of (2x7 + 8x + 6) cm. Its length is (2x + 2) cm. Find the width of the painting. 15. Instructors led an exercise class from a raised rectangular platform at the front of the room. The width of the platform was (3x - 1) feet and the area was (9x2 + 6x - 3) fto. Find the length of this platform. After the exercise studio is remodeled, the area of the platform will be (9x2 + 12x + 3) ft. By how many feet will the width of the platform change