Answer:

Let the breadth=x

the length =x+15

given perimeter=150

we know  

Perimeter of rectangle=2(l+b)

150 = 2( x+ x+15)

75=2x+15

60=2x

30=x

therefore breadth =30 cm  

length   =30+15=45 cm

check  

150=2(45+30)

150=2(75)

150=150  

LHS=RHS

hence proved.