Question

perimeter of rectangle=180cm,length=60cm,breadth=?

Answer 1

perimeter of rectangle=2(l+b)
180=2(60+x)
(180-120)cm=2x
x=30cm

Answer 2

$\bold {given : } \\ \\ perimeter \: of \: a \: rectangle : \\ \\ 180 \: cm \: \\ \\ length \: of \: a \: rectangle : \\ \\ 60 \: cm \: \\ \\ \\ \\ \: \bold{perimeter \: of \: rectangle : } \\ \\ \bold{\: 2 \: ( \: length \: + \: breadth \: )} \\ \\ \\ \\ 180 \: cm \: = \: 2 \: ( \: 60 \: cm \: + \: breadth \: ) \\ \\ 180 \: cm \: = \: 2 \times 60 \: cm \: + \: 2 \times \:breadth \\ \\ 180 cm \: = \: 120 \: cm \: + \: 2 \times \: breadth \: \\ \\ 2 \: \times \: breadth \: = \: 180 \: cm \: - \: 120 \: cm \: \\ \\ 2 \times breadth \: = \: 60 \: cm \\ \\ breadth \: = \: \frac{60}{2} \: cm \: \\ \\ \bold{breadth \: = 30 \: cm}\: \\ \\ \\ \\ \bold{breadth \: of \: a \: rectangle \: = \: 30 \: cm \: }$