Now that is "mathematical intelligence" pvb8. Check your calculator's batteries, or go yell at your math teachers for not showing you the formula "is over of equals % over 100." Cross multiply then divide.
Did you just talk about a 12% dilution and then subtract ,12 from ,60 and call it a 12% dilution? Just saying you shouldn't talk about "mathematical intelligence" and then do something "special" like that. WOW!!