Let the length and breadth of two rectangles be l1b1 and l2b2 respectively. According to the question ⇒11b1=480 ⇒12b2=480 They differ in length by 6cm and breadth by 4cm Then, length of second rectangle (l2)=(l1+6)cm Then, breadth of second rectangle (b2)=(b1−4)cm Perimeter of first rectangle =2(l1+b1) Perimeter of second rectangle =2(l1+6+b1−4) ⇒2(11+b1)+4 The difference in their perimeters is ⇒2(l1+b1)−2(l1+b1)+4 ⇒4cm