Answer: A. f(x) = − 1/3x +5
A student is running a 5-kilometer race, the total distance is 5 km.
He runs 1 kilometer every 3 minutes.
So the speed will be,
Speed = Distance/time
Speed = 1/3
Speed is the rate of change or slope and as the total distance is decreasing with time so it will in negative, thus;
Slope = -1/3
So when on x axis time and y axis distance is represented, 5 will be the y intercept.
Then put all the values in slope intercept form of straight line,
y = mx + c
y = -1/3x + 5
y = 5 -1/3x