Alegra2
1.a=1/2 bh, solve for h
2.s=1/2gt^2 solve for g
3. h=vt-5t^2, solve for v

A = 1/2bh...multiply both sides by 2
2A = bh...divide both sides by b
(2A)/b = h

s = 1/2gt^2...multiply both sides by 2
2s = gt^2...divide both sides by t^2
(2s) / (t^2) = g

H = vt - 5t^2...add 5t^2 to both sides
H + 5t^2 = vt...divide both sides by t
(H + 5t^2) / t = v