Weight of 0.2N and 0.5N are placed at the 30cm and 80cm marks respectively on a meter rule. If the meter rule balance horizontally on a knife edge at 60cm marks, calculate the weight of the meter rule

Hold your upper arm vertical and your lower arm horizontal with your hand palm-down on a table, as shown. If you now push down on the table, you’ll feel that your triceps muscle has contracted and is trying to pivot your lower arm about the elbow joint. If a person with the arm dimensions shown pushes down hard with a 90 N force (about 20 lb), what force must the triceps muscle provide? You can ignore the mass of the arm and hand in your calculation.

Please show me how to calculate where I need to place the stack of bricks on the right side in order for the beam to become balanced? Please refer to image.

3. Bob and Tom are on opposite sides of a 12 foot see-saw (teeter totter). Bob weight’s 96.6 pounds.The see-saw weight 75 pounds. Bob is sitting 1.5 feet from the left end of the see-saw. Tom is sitting 2 feet from the right end of the see-saw. The pivot for the see-saw is 6 feet from the left end. The see-saw is in balance horizontally. What is Tom’s weight?