No
R-12 freon freezing point (-252)........ R-22 freon freezing point (-256).......
No. Refrigerants can't be blended.
If introduced as liquid--invert container--yes it can be added to an existing charge of r-22 freon.
12 over 5 turned into a mixed number = 22/5
12 and 17/22
3 and 12/22
12 over 5 in a mixed number = 22/5
Automotive Freon is R-12 (or the new R-132 and R-134). Central air freon is R-22. They are not compatible because of their different boiling points. R-22 is being phased out through the year 2010, but there is no standard replacement.
They should never be mixed.
22/12 = 11/6 = 1 5/6
12/5 = 22/5