S (t) = 9t-4, find S (4)

For this problem, you need to substitute 4 in for your variable t. the original equation is S (t) and the one you need is S (4) - - in other words, evaluate this equation when t = 4.

S (4) = 9 (4) - 4

S (4) = 36 - 4

S (4) = 32 is your answer.