I am so confused on this one. I don't know if I'm suppose to use implicit differentiation like my other problems or what.

Problem: The length L of a rectangle is decreasing at the rate of 2cm/sec while the width W is increasing at the rate of 2cm/sec. While L= 12 cm and W= 5 cm, find the rates of change of

a) the area

b) the perimeter

c) the length of a diagonal in the rectangle