What are the factors of 16 that have a sum of 0

Ataxi company charges $2.25 for the first mile and then $0.20 per mile for each additional mile, or f = $2.25 + $0.20(m - 1) where f is the fare and m is the number of miles. if juan's taxi fare was $6.05, how many miles did he travel in the taxi? if juan's taxi fare was 7.65, how many miles did he travel in taxi

Can you me find the missing length. i attached an image.

With both problems. a.s.a.p directions on photo ^