In the following lever system, what is the clockwise torque?

Answer: The total clockwise torque is 900N*m
Explanation: The torque is defined as:
Torque = Force*distance to the axis.
Here there are two torques in opposite directions, if we consider the clockwise direction as the positive one, we have:
T1 = 200N*6m = 1200N*m
T2 = -300N*1m = -300Nm
Where T2 is negative because the torque is anticlockwise.
Another way to think this is to put the zero of our x-axis in the pivot point and say that the x-axis grows to the right. In this model, the distance of T1, is positive 6 meters, and the distance for T2 is negative 1 meter, so the signs match with the ones that we had.
Now we have that the total torque is equal to the sum of all the torques; so:
T = T1 + T2 = 1200N*m - 300N*m = 900N*m