



 
Hi Thomas, Suppose the length of the rectangle is $L$ m and the width is $W$ m. You know two facts that you want to use to produce two equations in $L$ and $W.$ First the length is twice the width so $L = 2 W.$ The second fact is that the perimeter is 68 m. The perimeter is $L + W + L + W$ so your second equation is $2L + 2W = 68.$ From the first equation you can substitute $L = 2 W$ into the second equation and solve for $W.$ I hope this helps,  


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