#1) Luis stated that when you are converting meters to centimeters your answer will be larger than your original number.

My answer is yes because centimeters are smaller .
(Is my answer OK )

#2) 8/9 + 1/3= 33/27= 1(12/27)= (I'm stuck here)

#3) 6/8-2/6=2 (18/20) =2 (9/10) is this ok.

#1) Yes

#2) I'm not exactly sure what you want. If you just want another way to put the three, I guess it could be 11/9 or 13/9.
#3) Same as #2, what exactly do you want? 5/12 or 29/10