Answer
See answer below
Work Step by Step
We need to choose conversion factors that the original units (yards and seconds) can divide out, leaving us with the units we need.
Here we have the speed of light represented as $3.0 \times 10^{10}cm/s$
Using appropriate conversion factors:
$\frac{3.0 \times 10^{10} cm}{1 s}.\frac{1 mi}{160934 cm}.\frac{3600s}{1h}$
$\frac{1 mi}{160934 cm} \rightarrow $ This conversion factor cancels cm and leaves miles.
$\frac{3600s}{1h} \rightarrow $ This conversion factor cancels seconds and leaves hours.
