This may no longer apply but the Ditloid answer is 12 Provinces of Canada.
NOTE There used to be 10 provinces and 2 territories - now increased to 3.
12 picture cards in a deck
12 Picture cards in a deck
If we're talking strictly algebra. 12 equals p of c can be written as: 12= p(c) meaning, 12 is the answer for some function p, when c is the variable.
50 Per Cent Equals One-Half
Was thinking Connecticut when I read this, but then gave up on that. Not gonna give it to you, but think about Canada
8 = Pints in a Gallon
This is a Ditloid. The answer is 78 = Atomic Number of Platinum
The solution to this ditloid is: 85 = Keys on a Piano
4 Cardinal Points of the Compass
8 = Points for potting the black. What sport is that in?
13 Hearts in a Pack of Cards.
2 Point Four Children