Learn Polish: Prom kursuje co czterdzieści pięć minut. - The ferry runs every forty-five minutes.

In Polish, co is used to express distributive frequency, meaning how often something happens. When followed by a time phrase, it translates to 'every'. The time expression that follows co takes the accusative case, though for a number phrase like czterdzieści pięć, the accusative form looks identical to the nominative.

Why is the word for minutes in the form minut rather than minuty?

The noun takes the genitive plural form minut because it is governed by the number pięć (five). As a reminder from earlier lessons, Polish numbers ending in 5 or higher require the noun that follows them to be in the genitive plural. If the ferry ran every two minutes, you would use the nominative/accusative plural co dwie minuty, but 45 triggers the genitive rule.

Since the time phrase after co is in the accusative case, why doesn't the number 45 change its form?

For non-masculine-personal items, the accusative form of a number is exactly the same as its nominative form. The entire block of words czterdzieści pięć minut acts as the accusative time phrase after co, but you don't see a visible case ending change because the accusative of czterdzieści pięć is simply czterdzieści pięć.

Why use the verb kursuje instead of a regular verb of motion like pływa (sails)?