Answer
$x=14$
Work Step by Step
Let x = the unknown number
Then
"the sum of 4 and a number" means $4+x$
"twice the sum" means $2(4+x)$
Thus, the equation that represents the situation is:
$2(4+x)=36$
Use the distributive property to simplify.
$(2\times4)+2x=36$
$8+2x=36$
Use the addition property of equality to subtract 8 from both sides of the equation.
$8+2x-8=36-8$
$2x=28$
Use the multiplication property of equality to divide both sides of the equation by 2.
$2x\div2=28\div2$
$x=14$
