ACT Math Practice Question

It took Sam $x$ minutes to bike the $d$ miles from home to work. Returning home on the same route, it took Sam $y$ minutes. On the way home his average speed was 2 times his average speed on the way to work. Which of the following equations gives $y$ in terms of $x$?

1. A.$y = \frac{x}{2}$
2. B.$y = x - 2$
3. C.$y = x + 2$
4. D.$y = 2x$