Answer:
8.65 miles
Explanation:
The total of his short runs are 9.35 so you need to find out how many miles he has left till he reaches 18 miles.
The equation you can use is 9.35 + x = 18 x will equal the number of miles for the long run.
9.35 + x = 18
to isolate x you will subtract 9.35 from both sides.
you will get:
x = 8.65
8.65 miles