I think that the missing word here is:
"with the amount of the material that Michelle has"
Let's say that her landing strip is x miles long, then its area would be:
\(\frac{1}{6} *x\)
We also know how big it is:
\(\frac{1}{6} *x= \frac{1}{1 500}\)
now, let's multiply both sides by 6:
\(\frac{6}{6} *x= \frac{6}{1 500}\)
\(1 *x= \frac{3}{750}\)
\(x= \frac{1}{250}\)
So the answer is that it would be \(x= \frac{1}{250}\) miles wide
