Question 670884
{{{18-6a=4a-4(a+3)}}} use distribution to expand the term in parens on the right side
{{{18 - 6a = 4a -4a - 12}}} put all the terms with a on one side and all the consants on the other
{{{18+ 12 = 4a - 4a + 6a}}} simplify
{{30 = 6a}}} solve for a by dividing both sides by 6
{{{30/6 = a}}}
{{{5 = a}}}