Willa and Westley are siblings who built a hair salon business from the ground up. They are now contemplating opening an additional salon location. The estimate to open an additional salon would mean adding $1 million in expenses and a profit of $2 million in total over the next 5 years (all other things equal). Willa and Westley decide

to take on the new salon because the expected marginal benefit is 2 million in the course of five years.

Explanation:

If Will and Westley  were to gain $2 million in the course of five years after opening the salon, then the  yearly profit will be;

2million/5 = 400000.

so yearly profit is 400000.

note from the above:

My conclusion is that as expected benefit in the course of five years of running the  suppose salon business is $2 million which outweigh (is greater than) the expected cost of  $ 1 million that was used in starting  the salon business, it is my advise that Will and Westley should take (start)on the new Salon business as it will yield a good profit.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."