Solve. 4/7 = 21/ x - 3a. x = 15b. x = 94c. x = 39 3/4d. x = 12 3/7

4/7 = 21/ (x - 3)

multiply by (x-3) on each side

4(x-3)/7 =21

multiply by 7 on each side

4(x-3) = 21*7

distribute

4x-12 = 147

add 12 to each side

4x = 159

divide by 4

x = 159/4

change back to a mixed number

4 goes into 159 39 times with 3 left over

39 3/4

Choice C

if you are saying purchasing 3 social media ads and one newspaper ad counts as one purchase then there are:

6 purchases

if you are asking how many of each then:

18 social media ads

6 newspaper ads