Parentheses Placement IF/AND Formula?

Hello,
I need help with the parentheses placement for some (IF/AND) formulas the result isn’t correct for some and Excel gives me errors messages for others. If you could review the formulas and see if which ones contain errors and which ones are correct it would be greatly appreciated.

Thank you.

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=AND((Q6-P6)/(O6-P6)>=0.6,(N6-P6)/(O6-P6)>=0.6)

I might be wrong but I think order of operations states that you are doing this:

=AND((Q6-P6)/(O6-P6)>=0.6,(N6-P6)/(O6-P6)>=0.6)
Then dividing the TRUE/FALSE by (N6-P6)

Try
=AND(((Q6-P6)/(O6-P6))>=0.6,((N6-P6)/(O6-P6))>=0.6)

Excel performs calculations prior to comparisons.

If you click Evaluate Formula on the Formulas ribbon you should see where your errors are.