A quadrilateral is a shape with four sides. The perimeter of a quadrilateral is the sum of the lengths of its four sides.

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

2a x 5b = (2 x 5) (a x b) = 10ab

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

-4x + 9 = \( \frac{x}{-8} \)
-8 x (-4x + 9) = x
(-8 x -4x) + (-8 x 9) = x
32x - 72 = x
32x - 72 - x = 0
32x - x = 72
31x = 72
x = \( \frac{72}{31} \)
x = 2\(\frac{10}{31}\)

The formula for circumference is circle diameter x π:

c = πd
c = 19π