Force & Motion: Find Max Weight of Block A for Stationary System

[Solms]

Hi, iam new here and would like some help with my high school physics. i would like to know the steps (and explanations), not just the answer. since i need to do good on the tests.

Block B weighs 711 N. the coefficient of static frcition between block and the table is 0.25; assume that the cord between B and the knot is horizontal. Find the maximum weight of block A for which the system will be staionary.
.../|(wall)
...../..|
.../...|
(B)----o(30degrees)
____...|
table|..|
...(A)
(ignore the periods)

 

[Päällikkö]

You are supposed to show what you've tried:
https://www.physicsforums.com/showthread.php?t=28

Draw a free body diagram.
What is the force pulling B off the table? How is this force affected by A's weight?