There are 8 bottles and 4 cups on a desk. Abby says that the ratio of bottles to cups is 8:4, and Betty says that the ratio should be 2:1. Who is right?

8:4 = (8 ÷ 4) : (4 ÷ 4) = 2:1

So, 8:4 and 2:1 are equivalent ratios. Both ratios express the same relationship between the number of bottles and the number of cups.

Thus, both Abby and Betty are right.