A company $is$ working $on$ a project with a budget $of$ $$1000.$ The planned value $asof$ today $is$ $$400.$ The project $is30\%$ complete and $60\%of$ the budget has been spent.

a$.)$ According to the budget, the cost variance is:

b$.)$If the company continues to spend at the same rate, the project cost will be:

c$.)$ What is the estimate to complete $($ATC$)?$

They answers are a$.)$ $$60$ b$.)$$$800$ c$.)$ $$560$

I know the answers but can someone help me understand the work required to achieve these answers.