Area equals length times width
A=l*w
40=l*w
Perimeter equals two times the length plus two times the width
P=2l+2w
26=2l+2w
Let's start with area. If we know all the factors, we can guess and check.
8*5=40 4*10=40 2*20=40 1*40=40
Let's try substituting 8 and 5 in to the perimeter.
26=2(8)+2(5)
26=16+10
26=26
So, the dimensions of the pen are 8 by 5.
