It is 10 3/5 miles of alston to barton. and 12 1/2 miles from barton to chester. the distance from alston to durbin, via barton and chester, is 35 miles. how far is it from chester to

So 10 and 3/5 ferom alston to barton
12 and 1/2 from barton to chester
from alston to durbin=35
it says that bartonand chester is between alston and durbin therefoe
 the distances are
alston10 and 3/5barton12 and 1/2chesterx---durbin
|35|
therefor

10 and 3/5+12 and 1/2+x=35

first we need to add 10 and 3/5 and 12 and 1/2
10 and 3/5=10 and 6/10
12 and 1/2=12 and 5/10
10 and 6/10+12 and 5/10=22 and 11/10=23 and 1/10
23 and 1/10+x=35
subtract 23 and 1/10 from both sides
x=11 and 9/10

the answer is 11 and 9/10 miles