Easy, do the same thing here,
change the numbers into whole numbers to be able to estimate:
8 ---->8
and
6 1/9---> 6
( 6 1/9 changes into 6, because 1/9 is not big enough to change into 9/9 making 6 1/9---> 7)
8-6=2
2 is your estimate.
8
-
6 1/9
change 8 into ----> 7 9/9 to be able to subtract
7 9/9
-
6 1/9
=
1 8/9
Thus, your answers are, 2 and 1 8/9.