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.

4a⁹ + 4a⁹ = 8a⁹

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)

The sum of the interior angles of a triangle is 180°:
180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 60° - 47° = 73°

A trapezoid is a quadrilateral with one set of parallel sides.

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.