Answer
According to the observer on the Earth, the taxi’s clock is running slowly, and the trip took 1.15 hours, earning the driver (1.15 hours)(10 stellars/hour) = 11.5 stellars.
Work Step by Step
Find $\gamma$ at v = 0.50c. It is $\frac{1}{\sqrt{1-v^{2}/c^{2}}}$, or $\frac{1}{\sqrt{1-0.50^{2}}}$, which is 1.15.
The factor $\gamma$ is the time dilation factor. Multiplying 1 hour by $\gamma$ gives 1.15 hours.