help!! i need to know which letter has the highest speed, the middlest speed and the lowest speed!!

Answer:
From highest speed to lowest speed:
A, C, B
Explanation:
On a position time graph, the slope of a line would represent the velocity, since the rate of change represents how many meters traveled in the given time.
The larger the slope, the faster the velocity; the steeper the line, the faster the speed.
Since line B is negative, you know that velocity is negative so it automatically has the lowest speed.
Out of lines A and C, since A is steeper, you know that A has a faster speed.
In conclusion:
A is the fastest
C is the middle
B is the slowest