One of the bases of a trapezoid has length 10, and the height of the trapezoid is 4. If the area of the trapezoid is 38, then how long is the other base of the trapezoid?
Area = (1/2) height * ( sum of base lengths)
38 = (1/2) (4) ( 10 + x)
38 = 2 ( 10 + x)
38 / 2 = 10 + x
19 = 10 + x
19 - 10 = x = 9 = the other base length