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.

y = 2x

step-by-step explanation:

if you divide each number in the sequence, you'll see that they all have a multiple factor of 2. each number in the series, and any other numbers which may continue, will be multiplied by 2. therefore, y is the next number in the sequence, and x is the current one, so, our formula will be y = 2x.

9 sandwiches per hour

step-by-step explanation:

when we have a rate, we want a 1 in the denominator

27/3 = 9

27 sandwiches/ 3 hours = 9 sandwiches/hour