How it works
APR means annual percentage rate: the yearly price of owing, as a percent of what is owed. Percent means out of one hundred, so 20 percent is 20 in every 100.
For Ana, who owed 60 coins, 20 percent means 2 extra for every 10 owed. Sixty is six tens, so a whole year costs 12 extra.
The yearly price is shared across the months: six months costs 6, three months 3, one month 1. Think of three things multiplied: the coins owed, the percent and the time.
In Larkspur, paying the whole bill by the due day adds no extra, so the APR matters when something is left owing. On an offer, ask three things: the APR, the due day and any fee.