A blank is a unit rate with a denominator of 1 unit. What is the the blank?

A unit rate is a ratio that has a denominator of 1. A unit rate is also called a unit ratio. (They mean the same thing.)

/frac{5}{4} and 3:8 and 40/mbox{ to }10 are ratios, but they are not unit ratios.

/frac{1.25}{1} and 0.375:1 and 4/mbox{ to }1 are unit ratios.

Any ratio can be converted into a unit ratio by dividing the numerator and the denominator by the denominator.