How to get a profit percentage of two columns in a pivot table ?

[lemonteadrink]

I have a pivot table that is pulling data from another table. From the table that Iam pulling the data from there are a few columns. How do I get the percentage profit in a new worksheet pivot table Column if the table that Iam pulling the data from doesn't have a column that shows the percentage profit and is a table generated from an in-house system pasted onto excel ? How do I get the profit percentage of two columns contract sum and cost in the new pivot table ?​