Question

find the breadth of a rectangle whose length is 12 cm and perimeter is 40 cm.

Answer 1

2{l+b}=40
l=12
2{12+b}=40
12+b=20
b=8cm

Answer 2

Length of rectangle = 12 cm

breadth = b

perimeter = 40cm

we know that:

$perimeter = 2(l + b) \\ \\ 40 = 2(12 + b) \\ \\ 12 + b = \frac{40}{2}$

$12 + b = 20 \\ \\ b = 20 - 12 = 8 \: cm$

breadth of rectangle is 8 cm.