Geometry Question for Title 1 Schools: Perimeter & Length Question?
8) If the length of a rectangle is twice the width of it, what is the length if the perimeter is 30?
Perimeter is the sum of the sides of shape
Perimeter for rectangle “p” = 2 (length “l” + width “w”) to cover all 4 sides.
Since “l” is twice “w”, then l = 2w
p = 2 (l + w)
30 = 2 (2w + w)
30 = 2 (3w)
We have to make “w” subject of formula, so we first move 2 to the other side, then 3. When you move to the other side, addition becomes subtraction, multiplication becomes division, and vice versa.
30/2 = 3w (2 was a multiplication at the other side)
15 = 3w
15/3 = w (3 multiplied w at the other side)
5 = w
If the width is 5, then the length must be 10.