18. Which of the following groups of numbers are all prime numbers?
A. 7, 17, 29, 49
B.2, 3, 5, 9
C. 2, 5, 15, 19
D. 3, 11, 23, 31

D

Step-by-step explanation:

3,11,23, and 31 can only be divided by 1 without becoming a decimal.

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).

a reflection across the x axis and a 90 degree rotation left and right.