Answer:
(a) 19.25 N-m
(b) 25.67 N-m
(c) 0 N-m
Explanation:
Given:
Length of the pedal arm (L) = 0.177 m
Downward force
= 145 N
Magnitude of torque is given by the formula:

Where, 
(a)
Given:
°
Therefore, torque is given as:

Therefore, the torque is 19.25 N-m.
(b)
Given:
°
Therefore, torque is given as:

Therefore, the torque is 25.67 N-m.
(c)
Given:
°
Therefore, torque is given as:

Therefore, the torque is 0 N-m.
I expect that they will <em>add</em>, and their effect at every location will be the <em>sum</em> of their individual effects at that location.
For example:
If they're acting at the same point and in opposite directions, the effect will be the same as a single force at that point, with strength equal to their difference, and in the direction corresponding to whichever one is stronger.
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