Question

f the force (at 90∘ to the lever arm) applied is 15 N and it is applied at 2.0 m from the pivot point (point of rotation), what is the torque on the lever?

Answer 1

15*2=30Nm of torque
the fact that it is 90 degrees to the lever means that the force is transferred directly tot he pivot; at a different angle you would multiply your answer by the sin of the angle to find the side of the triangle the force is exerted, but at 90 degrees sin(90)=1, so multiplying 30Nm by 1 is the same result.
If you are confused by this I can try to explain it further