Answer
(a) 228 miles
(b) 57 miles
Work Step by Step
(a) To find the number of miles traveled, we multiply the fraction $4/5$ by the total trip length ($285$ miles):
$\frac{4}{5}*285=\frac{4*285}{5}=\frac{4*57}{1}=228$ miles
(b) To find the number of miles that remain, we subtract the miles travelled from the total trip length:
$285-228=57$ miles
