Question 337043
Since the total number of blocks that Jarilyn ran was 42 blocks and her path was a rectangle, we can say that the perimeter of this rectangle is 42.
The formula for the perimeter of a rectangle is:
{{{P = 2(L+W)}}} where L = length and W = width. and P is given as 42, so...
{{{42 = 2(L+W)}}} If we divide both sides of the equation by 2, we get...
{{{21 = L+W}}}.
But we are told that the length (L) is twice as long as the width (W) or {{{L = 2W}}} so we can put this in place of L in the formula for the perimeter.
{{{21 = (2W)+W}}} which simplifies to...
{{{21 = 3W}}} and if we divide both sides by 3, we get...
{{{7 = W}}} and {{{L = 2(7)}}} = {{{14}}}
The length of her run was 14 blocks and the width was 7 blocks.
This seems a little advanced for fourth grade math!