The variable x has had the following done to it: • multiply by -1/5 • add 9
We want to "undo" these operations in reverse order. • undo "add 9" by "add opposite of 9" .. -x/5 = -6 . . . . . . . -9 added to both sides of the equation
• undo "multiply by -1/5" by "multiply by -5". We choose -5 because it is the multiplicative inverse of -1/5. That is (-1/5)*(-5) = 1. .. 1x = (-5)*(-6) .. x = 30
