A rectangle initially has width 8 meters and length 6 meters and is expanding so that the area increases at a rate of 3 square meters per hour. If the width increases by 20 centimeters per hour how quickly does the length increase initially? [hint: Using the product rule, if you know any two of the derivatives you can work out the third one. Here you know A=L*W and A' and W'.] centimeters per hour