If the force (at 90 degree to the lever arm) applied is 15 n and it's applied at 2.0 m from the pivot point (point of rotation), what is the torque on the lever?

The formula to calculating the torque is this:
τ = r F sinθ
where 
τ is the torque
r is the distance from the pivot point
θ is the angle from the lever arm where the force is applied

Plugging in the values:
τ = 2.0 m (15N) sin 90
τ = 30 N m