Answer
$a) ~2r^2 \\ b) ~6r$
Work Step by Step
(a) The length of the rectangle is $l=r$ and the width of the rectangle is $2r$.
So, the area of the rectangle is:
$A(r)=length \times width =r\cdot2r=2r^2$
b) The length of the rectangle is $l=r$ and the width of the rectangle is $2r$. The perimeter will be the length of the wire:
$P(r)=2*(length+width)=2(r+2r)=(2)(3r)=6r$
