Perimiter=2L+2W
w=x
P=80
80=2L+2x
diviide by 2
40=L+x
40-L=x
40-x=L
the area is found by legnth times width
LW or Lx
for a maximum area, try to get the legnths of the sides the same
therefor
L=W=x for max area
40=x+x
40=2x
divide 2
20=x
max area =legnth times width=20^2=400
note: all squares are rectangles, but not all rectangles are squares
L=40-x
A=(40-x)(x)
max area=400 cm^2
3 pounds bc there is 5 triangles for 15 pounds of squares
The answer would be 18*18*18=5832
Good luck ^-^