If one gallon = 4 quarts Then 5 gallons = x quarts
To solve this we can set up a porportion
1/4 = 5/x
To solve the porportion we need to find the rule so how to we get to 4 from 1? Well we can multiply 1 by 4 to get one right?
So if this is true, 1 x 4 = 4 then 5 x 4 must equal x
5 x 4 = 20 so the answer would be 20 quarts are in 5 gallons
Another way to look at this is that you have 5 gallons and in each gallon is 4 quarts to if there is 4 quarts in every one gallon then that’s just 4 + 4 + 4 + 4 + 4 or 5 x 4