Can someone explain the diffrence between first class, second class, and third class levers?

The answer you're looking for is that, 1rt class levers is that, the fulcrum is in the middle and force is being applied to one side of the lever, and the resistance on the other side for example think of a seesaw. A second class lever has load between the effort and the fulcrum. Like a wheelbarrow. The wheel's axels is the fulcrum and the handles are the effort. The load is between these two. Finally, a third class lever is when the input force is between the output force, such as a baseball bat. The handle of the bat is like a fulcrum. You input the force onto the bat, causing the output force to be pushed against the ball as it hits. Hoped this help you :@) 

Multiplication property of zero