## Introductory Algebra for College Students (7th Edition)

$x=14$
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. $2x\div2=28\div2$ $x=14$