Need Help Changing Divisor based on if a cell has a value

[survivoropoly007]

I am trying to create a formula that tracks overtime percentage essentially. My goal is that if the cell for week one has a value I want to divide that number by 40, if there is a value in week 1 and week 2 I want to divide the sum of the values by 80, if there is a value in week 1, week 2, and week 3 then I want to divide the sum by 120, and so one for week 4 and week 5. I was thinking and =IF function but I'm not sure if it is doable with that. Any thoughts?

[Special-K]

Try

=IF(COUNTA(A1:E1)<>0,SUM(A1:E1)/COUNTA(A1:E1)*40,0)

Explanation:
Add up the weeks A1:E1
Divide by the number of weeks that have been entered multiplied by 40
1 week 40
2 weeks 80
3 weeks 120
4 weeks 160
5 weeks 200

If 0 weeks filled then output 0

[survivoropoly007]

Thanks so much for the help, I will try that tomorrow morning, I think I ended up getting it to work through a very convoluted IF statement, but yours looks much simpler. I appreciate the help!