Question 748970
Let x represent the number you are looking for.  Then the sum of the number and 4 is (x+4) and twice that sum is 2(x+4), which is equal to 20:

{{{20=2(x+4)}}}

Distribute:

{{{20=2x+8}}}

Subtract 8 from both sides:

{{{12=2x}}}

Divide both sides by 2:

{{{6=x}}}