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

If the perimeter was 30 cm ... then the length had to be 10 and the width had to be 5. When doubled ... those numbers turn to 20 and 10, then find the perimeter with those new numbers ... (10+10+20+20) which the new perimeter is 60 cm.

if the length and width of the rectangle be doubled in size, the perimeter will be 4 times the original

new perimeter = 30*4 = 120cm