Answer:
Ratio: 4 cups of water / 1 cup of sugar
Explanation:
You kind of already answered your own question but I will try to help clarify stuff further. Basically, ratio just refers to a proportion. Therefore, it's always written out as a fraction.
The first unit mentioned usually is the unit that goes on top of the fraction, so the other unit is the one that goes on the bottom. The top unit is being divided by the second unit.
Therefore, it would just sound like "4 cups of water PER 1 cup of sugar."
If they asked you to find out # of cups of water for 5 of cups of sugar, then you would just multiply those proportions:
4 cups of water 5 cups of sugar 20 cups of water
----------------------- x ------------------------- = ----------------------------
1 cup of sugar 1 1
Final answer here: 20 cups of water
The cup measurements are on opposite sides so that the unit itself can also cancel out. You can also double check your answer by dividing 20 cups of water by 4 cups of water (because this would give you the proportional amount of sugar the 20 cup measurement of water needs).