Answer:
length = 10 cm; width = 25 cm
Explanation:
Let's call the length 2x and the width 5x. Since perimeter can be calculated by multiplying the sum of the length and width by 2 we can write:
2 * (2x + 5x) = 70
2 * (7x) = 70
7x = 35
x = 5 which means the length is 2 * 5 = 10 and the width is 5 * 5 = 25.