To add the mixed numbers, add the whole numbers first: 2+1+1=4.
Now to add the fractions. Common denominator is 72.
¼=18/72, ⅞=63/72, ²⁄₉=16/72, added together is (18+63+16)/72=97/72=1²⁵⁄₇₂.
So the total distance so far is 4+1²⁵⁄₇₂=5²⁵⁄₇₂.
We now need to subtract this from 8⅖.
Subtract 5 from 8 first=3.
To subtract the fractions we need the common denominator of 5 and 72, which is 360.
⅖=144/360 and ²⁵⁄₇₂=125/360.
So (144-25)/360=19/360. So the distance to go is 3¹⁹⁄₃₆₀ km.