don't understand these problems
A = ¹/₂bhA = ¹/₂(4z² - 10)(8z)A = ¹/₂[4z²(8z) - 10(8z)]A = ¹/₂(32z³ - 80z)A = ¹/₂(32z³) - ¹/₂(80z)A = 16z³ - 40z