Answer :
Substitute 3.5 for t
h(t) = -5(3.5)•(3.5) + 20
= -5•12.25 + 20
= -61.25 +20
= -41.25
If your initial equation is correct
h(t) = -5(3.5)•(3.5) + 20
= -5•12.25 + 20
= -61.25 +20
= -41.25
If your initial equation is correct