A cyclist travels $300\,\text{m}$ up a slope in $50\,\text{s}$. She then comes back down the slope in $25\,\text{s}$. What is the average speed for the entire journey?
- A$4.0\,\text{m s}^{-1}$
- B$8.0\,\text{m s}^{-1}$
- C$9.0\,\text{m s}^{-1}$
- D$16\,\text{m s}^{-1}$