Find S21 for the following arithmetic series: a1 = -2 and d = 8

16

step-by-step explanation:

2 x 40 = 80

80/5

= 16

,xzgv

step-by-step explanation:

; oqirjg'

c

-by-step explanation:

it would be c

the revenue of the fitness center, y, is the product of two factors: the number of members and the fee paid by each member. there are 320 members now, but number of members goes down by 10 for each $5 increase in fees, so if x is the number of $5 price increases then members is equal to (320 - 10x). since the fee is currently $45, and the fee increases by $5 for every price bump x, the fee is given by (45 + 5x). so, revenue y is given by y = (320 - 10x)(45 + 5x).