Step-by-step explanation: To add or subtract two fraction, you need to find a common denominator. The easiest way to do that is to just multiply the denominators of the two fractions together. 3 x 4 = 12 so I'll use 12 as my common denominator. Now that we have that, we have to convert the numerators. We must multiply the numerators by the same number we multiplied or denominators by to get the common denominator. 3 x 4 = 12, 4 x 3 = 12, 2 x 4 = 8, 3 x 4 = 12. Now the fractions we have are 9/12 and 8/12. Since they have the same denominator now we can add them. 9/12 plus 8/12 equals 17/12 or 1 and 5/12 written as a mixed number. We also add the whole numbers. 1 plus two equals 3. 3 plus 1 and 5/12 equals 4 and 5/12.
