Algebra-1

A unit rate is a ratio where the second quantity (the denominator) is 1. It represents how much of one quantity corresponds to a single unit of the other.

40 songs per album is a unit rate because it compares 40 songs to 1 album, making it a direct comparison to 1 unit of albums.

For option A, 90 units in 3 days

This is not a unit rate because it compares 90 units in 3 days, not 1 day. To turn this into a unit rate, you would divide 90 units by 3 days.