Compare the rates to find which is the best value. 3 greeting cards for $13.50

9 greeting cards for $38.25

6 greeting cards for $23.40

8 greeting cards for $32.80

step-by-step explanation:

we are given

since, we have to isolate x on anyone side

so, we can move all x terms on one side

subtract both sides by 2x

add both sides by 9

divide both sides by 4

we get

60%

94

step-by-step explanation:

average the numbers and use a variable to figure out the minimum to get a 90.

(79+94+91+92+x)/5=90

x = 94