CPM Homework Help : CALC Problem 8-113

The length of a rectangle is increasing at a rate of $6$ cm/s and its width is increasing at a rate of $2$ cm/s. When the length is $30$ cm and the width is $15$ cm how fast is the area of the rectangle increasing?

Hint 1:

$A = lw$

Hint 2:

Implicitly differentiate the Area function with respect to time.