Answer :

First find common denominator...
1/9*8/8= 8/72
5/8*9/9= 45/72

then add...
45+8= 53
so...
53/72 which is already in simplest form

then just add the whole numbers...
1+3 =4

and your answer is...
4 and 53/72
1 1/9 + 3 5/8 is 4 53/72.
My reason is you must equalize 1 1/9 to 1 8/72.
Then equalize 3 5/8 to 3 45/72.

Now add them together and do not add the denominators. Add the numerators, and the whole numbers. Simplifying is unnecessary. The answer should be 4 53/72.