Find X in Rectangle: Solving with Perimeter of 18 and Side Length 3

Question

If the rectangle below has a perimeter of 18.

Calculate X using the given data:

00:00 Find X

00:03 Use the rectangle perimeter formula - 2 times the sum of sides

00:07 Substitute appropriate values according to the given data and solve for X

00:13 Properly distribute terms - multiply each factor

00:24 Solve each multiplication separately and then sum

00:30 Isolate X

00:38 And this is the solution to the problem

Since we are given the perimeter, and in a rectangle opposite sides are equal, let's add up all the sides:

$X+X+3+3=18$

$X+X+6=18$

$2X=18-6$

$2X=12$

Let's divide both sides by 2:

$X=6$