Since the greatest common factor of 312 and 99 is 3, we can simplify the fraction and show the same amount
312
99
 = 
312 ÷ 3
99 ÷ 3
 = 
104
33
Therefore, 104/33 is simplified fraction of 3.15 repeating. Since this is an improper fraction, converted to mixed number is: 
104
33
 = 3
5
33