Answer
The U.S. strategic oil reserve would last about 73 days.
Work Step by Step
U.S. strategic oil reserve (2009): $726.6~millions~of~barrels$.
Import oil rate: $\frac{10~millons~of~barrels}{day}$
$Time~left=\frac{726.6~millions~of~barrels}{\frac{10~millons~of~barrels}{day}}=72.66~days\approx73~days$
