i have 3 fields i'm trying to find the percent for product sales = 3000000 , Stock Cost = 400000 , and labor Cost = 300000 , now when i select these i get my percent ( using pie chart ) i know how to get the percent of 1 number from Product Sales but how do i take 2 and 3 from it and get all the right percents for the labor and Stock Cost

can someone show me a formula to get all these