So the length of a rectangle is 7cm less than three times the sum of the width and 5. Therefore:

L=3(w+5)-7

L=3w+15-7

L=3w+8

1) p=2L+2w

Insert the first equation for L:

p=2(3w+8)+2w

p=6w+16+2w

p=8w+16

2) p=88cm

88=8w+16 (Subtract 16 from each side)

72=8w (Divide by 8 on each side)

w=9 cm

So:

88=2L+2(9)

88=2L+18

70=2L

L=35 cm

(1) P=l+l+w+w Perimeter is just all the sides added together.

(2) What is the width? if the width is unknown, than the length is 3(w+5)-7

1.length- 3(x+5)-7

width- x

P= 2(3x+8) + 2(x)

P=6x+16+2x

P=8x+16

2.)

88=8x+16

72=8x

9=x

length, since x=9 : 3(9+5)-7

27+15-7

length= 35cm