It costed $2.25 for the first mile so we already have part of the equation. Then it's $0.20 per additional mile, the additional mile isn't given so it would be x. $2.25 + $0.20x = $6.05. If we subtract $2.25 from $6.05 we get $3.8. We divide by $0.20 and get 19. Which means he traveled 20 miles.
