Question 713879
A=20  P=18
Since the area of a rectangle is LW and the perimeter is 2L+2W, this becomes a system of equations...
LW=20
2L+2W=18

2L+2W=18 is the same as saying 2(L+W)=18, then dividing both sides by 2 leaves L+W=9.  What 2 numbers multiply to 20 and add to 9?  5 and 4