I was confused about how they solved this problem? Any explanation helps to make it more clear Thank you!!

c. An arrow is shot vertically upward at a rate of 112 feet per second. Use the projectile formula h = -16t2 + vot, to determine when height of the arrow will be 196 feet. 196=-16t2+112t 21+7 16t2-112t+196+0 (2t-7)(2t-7) 412-28t+49=0 =(2t-7)2=0 t=7/2