I hope this helps you
l=x+2
w=2x-5
(x+2)(2x-5)=56
2x^2-x-10=56
2x^2-x-66=0
2x +11
x -6
(2x+11)(x-6)=0
x=6
You know b=0 because it is passing through the orgin (0,0) and b is the y intercept. You input (-3,6) as (x,y)
A=g≈-32
v=⌠a dt since a≈-32
v=-32t+C, where C is the initial velocity, which we are told is 20 ft/s
v=-32t+20
h=⌠v dt
h=-32t^2/2+20t+C, where C is the initial height, so what is a reasonable initial height? How about 3 ft since we are swinging a bat around maybe our waist level... maybe :P
h=-16t^2+20t+3
Your choices may have made a different assumption about the initial height of course but you did not show your choices, but certainly it will be:
h(t)=-16t^2+20t+hi, where hi is the initial height in feet.
This of course ignores air resistance and flight dynamics of a spinning ball with seams, which will make a significant difference in real life :)