A mixture of fuel for a certain small engine should be 4 parts gasoline to 1 part oil. If you have 5 quarts of, oil how many quarts of gasoline will you need for a correct mixture

So the ratio of the first engine is 4 gasoline: 1 oil. 4:1 ratio. So the question is asking __ gasoline: 5 oil? Simple. For every 1 part of oil is 4 parts gasoline, so for the answer, you'd cross multiply.