7x - 81 = -2 + 72. First you add up the left side. This gives us: -2 + 72 = 70 So the equation becomes: 7× - 81 = 70 Now we add up 81 on both sides to get rid of the 81 on the left 7x = 151 Now divide both sides by 7 x = 151/7
For explanation: whenever a number passes a equal sign, it becomes its opposite. For example once the number 2 passes through the equal sign it become -2
