Question 53458
For your equation of {{{1/2 * x - 9 = 0}}}, multiply both sides by 2 to get {{{ 2 * (1/2 * x - 9) = 2 * 0}}}, which expands to {{{1*x-18=0}}}, which further simplifes to {{{x-18=0}}}.  Now add 18 to both sides to get x=18.