Question

WHAT IS THE RULE TO USE SHALL AND WILL?

Answer 1

Shall is used with first person pronouns ( for example I and we ) to form future tense and Will is used with second and third person forms. ( for example you , he , she ,it , etc ) 

Example of shall and will in sentence

I shall be late .

They will not have enough food.

However, when it comes to expressing a strong determination to do something, the roles are reversed: will is used with the first person, and shall with the second and third. For example:

I will not tolerate such behaviour.

You shall go to the ball!