1. 8/9 + 2/3 = ?
Note that the LCD here is 9. Transform 2/3 into 6/9. Then add: 8/9 + 6/9 = 14/9 (answer)
2. 5/6 + 12/15 =? The LCD is 90. Thus we have (75/90) + (72/90) = 147/90 (ans)
5 1/3 + 2 1/4=? The LCD here is 12. Thus, we're adding 5 4/12 to 2 3/12.
Adding the whole numbers produces 7; adding the fractions 7/12. Thus, the desired sum is 7 7/12 (answer).
4. 3/4 + 6/7
Here the LCD is 28. Thus, we're adding 21/28 and 24/28. We get 45/28 (answer).