Hi gnarrr, welcome to PF.
Please go through the rules of the PF.
Don't post the problems alone. Show your attempts. List the relevant equations. Still if you don't get, we will help you.
The first one
1. The problem statement, all variables and given/known data
Consider the bar to have negligible mass. How far from point 'A' must a downward force of 40.5 N be applied in order to achieve rotational equilibrium.
2. Relevant equations
3. The attempt at a solution
5x9.8x2.1 + 3.5x9.8x4.3 + 40.5xd = 0
i figured out the second one
First on is wrong.
If you want to take the moment about the fulcrum, you have to consider clockwise and counterclockwise moments and use proper sings.
If you want to take the moments about A, 40.5 N and 3.5 kg produce clockwise moment and the reaction due to all the forces on the fulcrum will produce the counterclockwise moment. Equate them to get d.
Separate names with a comma.