Respuesta :

Step-by-step explanation:

in a rect.

b:l=1:4

let,

"x" & "4x"

perimeter=20cm

thus,

2(l+b)=20

x+4x=20/2

5x=10

x=10/5

x=2

also

4x=4×2

=8

also ,area=

l×b

=8×2

=16

thus,area=16