12.28 is equal to 12 + 0.28. Since 0.28 is read as "twenty-eight hundredths", that's exactly how we write it in fractions: 28/100. Next, we need to simplify the fraction into its simplest form by looking for number that can be divided to both numerator and denominator. Hence, we have 12.28 = 12 + 28/100 = 12 + 7/25 = 12 7/25. Answer is 12 7/25.