first you make it an improper fraction:
8 5/6 = 53/6
4 9/10= 49/10
then you find a common denominator- 30
so then 53/6 would mulitply by 5= 265/30
49/10 multiplies by 3- 147/30
do calculation:
265-147= 118
118/30 and you can make it a mixed number and reduce to:
3 14/15