When you talk about the speed of a car, you usually say something in miles per hour. For example, you say, 'I drove 40 miles per hour.' Normally, you don't say, 'I drove 120 miles per 3 hours.' Figure out how to convert a rate like 120 miles per 3 hours to the unit rate of 40 miles per hour by watching this tutorial.
Can you do 100 sit-ups in 2 minutes? That's a rate! Driving a car going 40 miles per hour? That's a unit rate! Watch this tutorial to learn about rate and unit rate (and the difference!).
To master equivalent ratios, you need to practice. Follow along with this tutorial to practice filling in a table with equivalent ratios.