Patti's pet palace has a 90-gallon fish tank. when it needs to be cleaned, it can be drained at a rate of 2 gallons per minute. assuming the tank was full, and x represents the number of minutes the tank has been draining, which of the following equations represents the amount of water in the tank after x minutes?

y = 2x + 90

y = 90x - 2

y = 90 - 2x

y = 2x - 90