Answer:
105 cm ^ 2 / s
Step-by-step explanation:
We have that the area of a rectangle is given by the following equation:
A = l * w
being the length and w the width, if we derive with respect to time we have:
dA / dt = dl / dt * w + dw / dt * l
We all know these data, l = 15; w = 12; dl / dt = 5; dw / dt = 3, replacing we have:
dA / dt = 5 * 12 + 3 * 15
dA / dt = 105
Which means that the area of the rectangle increases by 105 cm ^ 2 / s
