There are a few approaches one could take to this problem, but since the numbers are a little awkward, I'm going to try to avoid as much calculation as possible. We could determine the distance travelled, then calculate the time it would take at 6 miles per hour, converting between minutes and hours, but there is a simpler way.
We know that \(distance = speed * time\)
We also know that in our problem the distance is constant. It is the same whether Carlos is driving or biking.
So \(distance = speed_1*time_1 = speed_2*time_2\)
What we're trying to find is the value of \(time_2\), so \(time_2=\frac{speed_1*time_1}{speed_2}\)
\(time_2 = \frac{9*22}{6} = 33\) minutes
Answer: B
Note that I did not have to convert the time into hours for this to work. The ratio of the times taken is the inverse ratio of the speeds, \(\frac{speed_1}{speed_2}=\frac{time_2}{time_1}\) so since we are dealing with ratios, the units could be anything, and no conversion is necessary. If we actually needed to calculate the distance, then we would need to convert the time into hours (or the speed into miles per minute).
_________________
Dave de Koos
GMAT aficionado