The function a(b) relates the area of a trapezoid with a given height of 12 and one base length of 9 with the length of its other base. it takes as input the other base value, and returns as output the area of the trapezoid. a(b)=12•b+9/2. which equation below represents the inverse function b(a), which takes the trapezoid's area as input and returns as output the length of the other base?