Need calculations help

I am trying to use an IF function with multiple calculations but sometimes one of the cell will contain a 0 and because it can't divide by zero it won't give me the time I need. So I have to go in a edit the formula to skip that step and cell. I want to be able to just keep my formula in the entire column without having to edit to get the answer I need. Attached is an example of what is happening. Row one is what is currently happening row 2 is what I need the answer to be in column C but again to achieve this currently I have to alter the formula. Any help on the correct function/formula would be greatly appreciated