Answer:
Part A. 
Party B. Excluded value 19
Step-by-step explanation:
Given : 
Part A. Simplify the algebraic fraction.
Step 1- Write the expression

Step 2- In division same base powers get subtracted

Step 3- Divide 57 by 19
Therefore, 
Part B. Determine the excluded value(s) of the variable. In two or more complete sentence, explain how you determine the excluded value and why it cannot be possible value for the variable.
Excluded value of the variable is 19
because, 19 comes on both the side as the factor of 57 is 19×3
So we can write 57 in the form of 19×3 and by divisor of 19 it cancel out.
So, automatically 19 has to be cancel out in any situation you can also see in above steps.
Therefore, it cannot be possible value for the variable.