variance analysis

I am extremely sorry for asking the answer alone.I am doing my exams tomorrow and i found the below questions in the open tuition revision exam.I tried my best to find an answer but i couldnt figure it out.Thats why i asked you sir to get help.

Can i know what is incremental cost and how is the scrap value accounted?

Initial cost $300,000
Expected life 5 years
Est. Scrap value $20,000
Addition revenue from the
project – $120,000 per year
Incremental costs of the project – $30,000 per year
cost of capital 10%
calculate the NPV of the
project.