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:

00:08 Let's find the value of X.

00:11 Use the formula for the perimeter of a rectangle. That's two times the sum of its sides.

00:18 Now, put in the numbers from the problem. Solve for X.

00:22 Distribute the terms. Multiply each factor carefully.

00:32 Solve the multiplications one by one. Then add them up.

00:38 Next, we need to isolate X.

00:46 And that's how we solve 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:

$X=6$