Question:
The length \( x \) of a rectangle is decreasing at the rate of \( 5\;\text{cm}/\text{min} \) and the width \( y \) is increasing at the rate of \( 4\;\text{cm}/\text{min} \). When \( x = 8\;\text{cm} \) and \( y = 6\;\text{cm} \), find the rates of change of (a) the perimeter, and (b) the area of the rectangle.