Annika biked 37 \text{ km}37 km37, start text, space, k, m, end text this morning and another x \text{ km}x kmx, start text, space, k, m, end text in the evening. How many kilometers did Annika bike today?

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.