511 kilograms plus what = 720 kilograms

Jabari is power washing houses for a summer job. for every job, he charges an initial fee plus $30 for each hour of work. his total fee for a 4 -hour job, for instance, is $170 . jabari's total fee, f, for a single job is a function of the number, t, of hours it takes him to complete the job. write the function's formula.

When y’all answer can y’all explain too !

The ratio of wooden bats to metal bats in the baseball coach’s bag is 2 to 1. if there are 20 wooden bats, how many metal bats are in the bag?