Answer:
48 km
Step-by-step explanation:
Let us assume that, the distance of the track where they raced is x km.
We know that,
\(\text{Speed}=\dfrac{\text{Distance}}{\text{Time}}\)
or \(\text{Time}=\dfrac{\text{Distance}}{\text{Speed}}\)
Bob runs an average of 12 kilometers per hour. So time taken by Bob is,
\(t_1=\dfrac{x}{12}\)
Sue runs an average of 8 kilometers per hour. So time taken by Sue is,
\(t_2=\dfrac{x}{8}\)
Bob finishes 2 hours before Sue, so
\(\Rightarrow t_2-t_1=2\)
\(\Rightarrow \dfrac{x}{8}-\dfrac{x}{12}=2\)
\(\Rightarrow \dfrac{3x-2x}{24}=2\)
\(\Rightarrow \dfrac{x}{24}=2\)
\(\Rightarrow x=2\times 24=48\) km
