Final answer:
Phil's constant biking speed is 12.5 mph, which gives us the equation y = 12.5x, where y is the distance and x is the time in hours. This corresponds to option (a).
Step-by-step explanation:
The student has provided various distances traveled by Phil on his bike and the corresponding time it took to cover those distances. To write an equation that describes this situation, we need to determine the constant of proportionality, which is the same as finding the speed in this context.
For all given data points, we divide the distance by the time:
- 25 miles ÷ 2 hours = 12.5 mph
- 37.5 miles ÷ 3 hours = 12.5 mph
- 50 miles ÷ 4 hours = 12.5 mph
Since the speed is constant at 12.5 mph, we can use this to write the equation in the form y = mx, where y represents the distance traveled, m is the constant speed, and x is the time in hours. The equation that describes this situation is thus:
y = 12.5x
The correct answer aligns with option (a).