1 2/3 You take the 3 denominator multiply by 1 and add 2. you should get 5/3
4 7/9 you take the 9 multiply it by 4 and add 7. you should get 43/9
Then you need to find the common denominator to 5/3 multiply 3/3. you should get 15/9.
Now you can add 15/9 and 43/9 which equals
58/9 as an improper fraction but if you wanted a mix number its 6 4/9