Chapter $11$: Applying Excel: Exercise $($Part $2$ of $2)($Algo$)$

Requirement $2$:

Revise the data in your worksheet as follows:

If your formulas are correct, you should get the correct answers to the following questions.

a$.$ What is the ROI?

b$.$ What is the residual income?

Note: Negative amount should be indicated by a minus sign.

c$.$ Why is the residual income positive?

I am hoping someone can double check my answer, as I am really not confident in how I came up with the answers for part a and part b$.$

I also need help with part c$...$I am showing what the options are in the question.

I have also attached part $1$ to the question.

I have now added a photo with the $4$ formulas I used in beside column B $($of course they are just missing the $"="$ infront$)$