Let x be the height, in inches. Then the base is 3x+1 inch. The area of the triangle is; THEREFORE, your base equation is = 40 square inches. Then you simplify it x*(3x+1) = 80 3x^2 + x - 80 = 0 and solve it using the quadratic formula = = . You have two roots = 5 and , but only positive root is good as the solution to the problem. ANSWER. The height of the triangle is 5 inches.