Question

please answer this as fast as u can with the method as a 7 class student​

Answer 1

Answer:

l=16m. b=4m

Step-by-step explanation:

l= length, b=breadth

l=5b-4

perimeter =2(l+b)

40 =2(5b-4+b)

40 =2(6b-4)

40=12b-8

48=12b

b=48/12=4m

l=5b-4

=(5*4)-4

=20-4

= 16m

Answer 2

Step-by-step explanation:

Given,

perimeter of the rectangle=40 m

we know that,

perimeter of a rectangle= 2(l+b) .....eq 1

here, l=length, b=breadth

given condition:

l=5b-4 .....eq 2

from eq 1:

2(l+b)=40

l+b=20

l=20-b .....eq 3

equating eq 2 and eq 3

5b-4=20-b

5b+b=20+4

6b=24

b=4 m

substitute b=4 in eq 3

l=20-4

l=16 m

therefore

length=16 m

breadth=4 m