let

l = 20 cm the length of the rectangle

b = the breath of the rectangle

P = the perimeter of the rectangle

Its breath is 1/4 shorter than the length:

b = (1/4)l

b = (1/4)*20

b = 5 cm

the formula for the perimeter of a rectangle is:

P = 2(l + b)

P = 2(20 + 5)

P = 50 cm

the perimeter of the rectangle is 50 cm.

let

l = 20 cm the length of the rectangle

b = the breath of the rectangle

P = the perimeter of the rectangle

A = the area of the rectangle

Its breath is 1/4 cm shorter than the length:

b = l - 1/4

b = 20 - 1/4

b = 79/4 cm

the formula for the perimeter of a rectangle is:

P = 2(l + b)

P = 2(20 + 79/4)

P = 79.5 cm

the perimeter of the rectangle is 79.5 cm.