Atwelve-pack of 20-ounce water bottles sells for $4.78. the expression 20w represents the amount of water in a number of bottles. what does the variable w represent?

You are told that 20w = the amount of water in a number of bottles. You are also told that the amount of water in each bottle is 20 ounces. You can ignore the other information you're given, since it won't help you get your answer.

Since 20 (amount of water per bottle) is multiplied by w to get the amount of water in a number of bottles, that means w = the number of bottles.