Suppose that you are the manager of a software development company that has been

awarded a contract to develop an AI model. The developing process will last one year.

The client asked you to choose of the following payment plans:

Plan A: Pay you the price of $150000$$; $$

$40\%$

Plan B: Pay you the price of $142000$$ $$ C:

Plan C: Pay you the price of $155000$$ $

Using a $9\%$ normal interest rate compounded monthly, which payment plan

should you take

Suppose that you decided Plan B and found out later that project will cost you

$12000$$ per month. $\%?$