Solve for n in the proportion. If possible, first simplify the known fraction.

42 : 6 = 28/n

a. n=4

b. n=7

c. n=6

d. n=28

42:6 = 28/n

42/6 = 28/n

42*n = 6*28 ... cross multiply

42*n = 168

42*n/42 = 168/42

n = 4

Answer is choice A

As a check, we would plug n = 4 back into the original equation

42/6 = 28/n

42/6 = 28/4

7 = 7

Answer is confirmed