What Must the Reading on Scale A Be and the Mass of Block Z?

[jti3066]

Homework Statement

The weightless horizontal bar in the figure below is in equilibrium. Scale B reads 4.20 kg. The distances in the figure (which is not to scale) are: D1 = 7.5 cm, D2 = 6.0 cm, and D3 = 5.0 cm. The mass of block X is 0.97 kg and the mass of block Y is 1.89 kg. Determine what the reading on scale A must be.

Determine the unspecified mass of block Z.

Here is the diagram:

http://loncapa1.fsu.edu/enc/55/f90d8a024911f78dfa67c5a4b82c4e31d434fffb9e324ad1beb062f2a8a86b5f4b4acacc329e330ca47a2acba58743682d0f6370c013bd229ecc68ff61138f64532270835a981530.gif"

Homework Equations

Not sure..

The Attempt at a Solution

I am not sure where to even begin...Please help me solve this problem

 

[Seannation]

I doubt anyone can help you unless you either upload a stetch of the figure mentioned in the question or type in a diagram using your keyboard.

But from the question I reckon the problem is a bar sitting with two scales on either end. These sorts of problems involve bending moments. Just remember that since the bar is in equilibrium (no net forces acting upon it), the sum of all forces must be 0.