What is 1.8r+9=-5.7r-6

Using the side-splitter theorem, daniel wrote a proportion for the segment formed by luke segment de. what is ec?

The height of a flare fired from the deck of a ship in distress can be modeled by h(t)= -2(8t^2-52t-28), where h is the height of the flare above water and t is the time in seconds. a. find the time it takes the flare to hit the water.

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?