Final answer:
The football player took 15 seconds to reach the 20-yard line.
Step-by-step explanation:
To find the time it took for the football player to reach the 20-yard line, we can use the formula:
Time = Distance / Velocity
Since the player ran from the 50-yard line to the 20-yard line, the distance is 50 yards - 20 yards = 30 yards. The velocity is +2 yards/second. Plugging these values into the formula, we get:
Time = 30 yards / 2 yards/second = 15 seconds.