Could you please help me with this? And also please explain it thank you!

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.

If f(x) = 4x - 3 and g(x) = x + 4, find (f - g) (x)

I’m really confused and need to learn this