When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

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

An acute angle measures less than 90°, a right angle measures 90°, and an obtuse angle measures more than 90°.

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce -40 as well and sum (Inside, Outside) to equal 3. For this problem, those two numbers are -5 and 8. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 3y - 40
y² + (-5 + 8)y + (-5 x 8)
(y - 5)(y + 8)

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses:

(y - 6)(y - 3)
(y x y) + (y x -3) + (-6 x y) + (-6 x -3)
y² - 3y - 6y + 18
y² - 9y + 18