f + 8/9 = 9 1/9

Answer 1

9 1/9 = 82/9

so, now it's easier to do

f + 8/9 = 92/9
f = 74/9 = 8 2/9

or,

f + 8/9 = 8 10/9
f = 8 2/9

Answer 2

ty