The area of a trapezoid is equal to times the height times the sum of the bases .
Substitute the values of the height and bases ( and ) into the formula for the area of a trapezoid.
Add and .
Cancel the common factor of .
Write as a fraction with denominator .
Factor out the greatest common factor .
Cancel the common factor.
Rewrite the expression.
Multiply by .
Multiply and .
Divide by .