He used 11/12 of sugar.
(1) I multiplied the factors and denominators by eachothers denominators
(2) I ended up with the two converted fractions: 8/12 and 3/12. The reason for this step is because if the two fractions have the smae denominator, it helps make it easier to add the fraction.
(3) I added the fractions, getting the sum of 11/12
Good question!
