One base of a trapezoid is *decreasing* at a rate of $8$ kilometers per second and the height of the trapezoid is increasing at a rate of $5$ kilometers per second. The other base of the trapezoid is fixed at $4$ kilometers. At a certain instant, the decreasing base is $12$ kilometers and the height is $2$ kilometers. **What is the rate of change of the area of the trapezoid at that instant (in square kilometers per second)?** [[☃ radio 1]]