To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

2a + 2a = 4a

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 + 7)(y + 4)
(y x y) + (y x 4) + (7 x y) + (7 x 4)
y² + 4y + 7y + 28
y² + 11y + 28

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

6a - 7a = -1a

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

A right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.