Destiny designs necklaces. she uses between 15 and 20 yellow and blue beads in a ratio of 4 yellow beads to 5 blue beads.

What is the question here?

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.

The first answer is correct