Julie bought $8.64 worth of 57-cent stamps and 30-cent stamps. The number of 30-cent stamps was 6 less than the number of 57-cent stamps. Solve the equation 0.57 s + 0.3 ( s − 6 ) = 8.64 for s , to find the number of 57-cent stamps that Julie bought.

The number of 57-cent stamps that Julie bought is 12

Step-by-step explanation:

Given equation

0.57 s + 0.3 ( s − 6 ) = 8.64

Open bracket

0.57s + 0.3s - 1.8 = 8.64

Collect like terms

0.87s = 8.64 + 1.8

0.87s = 10.44

Divide both sides by 0.87

s = 12

The number of 57-cent stamps that Julie bought is 12

step-by-step explanation:

x = 3 ± √(5+y)