What is 12/3 in lowest terms

Divide.

12 over 3 is the same thing as saying 12 divded by 3. If you want to simplify it just pick a number that the top and bottom have in common (lowest common denominator?). For the example it would by 3.

so 12/3 can be simplified using 3 (12/3)/(3/3) = 4/1= 4