Question 287658
You must isolate x on one side of the equation.  To do this, you will subtract 13 from both sides of the equation.
So, 
13 + 2x = 3
-13 + 13 + 2x = 3 - 13
2x = -10
Now you will divide both sides by 2 to get x by itself.
2x/2 = -10/2
x = -5