mixed numbers are never fun, so let's make it easier by changing the mixed numbers to an improper fraction
what you do is:
multiply the denominator with the whole number and then add the numerator to your answer to get your improper fraction
3 4/6 = 22/6
1 1/3 = 4/3
2 1/4 = 9/4
22/6*4/3*9/4
numerators: 22*4*9 =792
denominators: 6*3*4=72
792/72= 11