How do you figure out the Variable Cost?

I am taking a college microeconomics class and do not understand how to figure out the variable cost. I found an equation that said VC= FC-BE (fixed cost minus break-even point=Variable Cost) however I learned that the to calculate the BE you look at the lowest Average Total Cost (ATC), but in order to figure out the ATC you do Total cost divided by Quantity, but then I don't know how to do that because I cannot figure out the VC. (TC equation is FC+VC). Any help would be greatly appreciated!