Can a line on a position-time graph have a negative slope?

Yes, when the velocity of the object is negative.

Explanation:

In position and time graphs, the slope of line indicates the velocity. Therefore negative slope of a position-time graph actually indicates negative velocity. Negative velocity is defined as the velocity of the object moving in an opposite direction.

The time graph reveals pertinent information about an object's velocity. For example, a small slope means a small velocity; a negative slope means a negative velocity; a constant slope (straight line) means a constant velocity; a changing slope (curved line) means a changing velocity.

the independent variable, or the one that is intentionally manipulated is the speed.

volts times amps 6 x 0.5 3w