Question 91766
Your goal, when solving a one-variable equation, is to isolate x, to do that you do opposite operations.

The first step is to eliminate 13 (constant term).

The opposite operation of "+" is "-", so I minus 13 on both sides of equation:

{{{x/2}}} +13 - 13 = 20 - 13

               -
 
{{{x/2}}} = 7

now to get answer, do the opposite operation again, the opposite of division
is multiplication:

{{{(x/2)*2 = 7*2}}}

so x = 14   <==== answer.