The 4th term is 135
n-1
you get it by using the formula Tn= ar <span />
A) 27, 81
b) -30,-15
c) -3, 1
d) -320, 1280
Given equation is 
Now it says to find f(2)
that simply means plug x=2 because we see that 2 is written in place of x in f(x) and f(2)



Hence final answer is 
For each child she spent $5 plus $15 = $20
120 divided by 20 = 6 subscriptions