Question

A rectangle has a perimeter of 30 cm. What would be the new perimeter if the length and width of the rectangle is doubled in size?

Answer 1

The new perimeter would be 60.

Let's say the length is 10 and the width is 5.

2 * 10 = 20 and 2 * 5 = 10

20 + 10 = 30 <== The old perimeter

If we double 10 and 5 we get 20 and 10 as the new length and width.

2 * 20 = 40 and 2 * 10 = 20

40 + 20 = 60 <== The new perimeter

Answer 2

Perimeter of the rectangle:
2 L + 2 W = 30 cm
2 ( L + W ) = 30 cm
If the length and width of the rectangle is doubled in size the new perimeter would be:
2 ( 2 L + 2 W ) = 2 · 2 ( L + W ) = 2 · 30 cm = 60 cm