The width of rectangle a is the sum of twice a number and 8. the length of the rectangle is 3 times as great as the width. if the perimeter is 96, find the length and the width.

width = 2n+8

length = 3 * width = 3*(2n+8) = 6n+24

Perimeter = 2(l+w)

                  = 2(  6n+24 + 2n+8)

                  = 2( 8n+32)

           96   = 16n +64

          -64            -64

        32  = 16n                              divide by `16

        2 = n

width = 2n+8 = 2*n + 8=  4 + 8 = 12

length = 3*width = 3*12 = 36

use this formula:

p(a\b) = p(a and b)/p(b).

take it from here.