What type of sentence is this?Our car broke down, so we came last.

Explanation

This sentence is an example of a compound sentence.It contains two independent clauses (main clauses):"Our car broke down" and "we came last"These clauses are joined by the coordinating conjunction "so", which indicates a cause-and-effect relationship between the two clauses. Both clauses could stand alone as separate sentences, but they are combined to show the relationship between the car breaking down and the consequence of arriving late.