Solving for x
5x - 8 = 2x + 7
subtract 2x from both sides
5x - 2x - 8 = 2x - 2x + 7
3x - 8 = 7
add 8 to both sides
3x - 8 + 8 = 7 + 8
3x = 15
divide both sides by 3
3x/3 = 15/3
x = 5
Check answer by replacing x with 5 in the orginal equation
5x - 8 = 2x + 7
5(5) - 8 = 2(5) + 7
25 - 8 = 10 + 7
17 = 17