Ashley is filling a tank with water at a rate of 5 gallons per minute. The tank already had 190 gallons of water in it. Suppose the tank holds a total of 300 gallons of water. How much longer will it take her to fill the tank? (The variable x is used to represent the number of minutes.)
The total amount of water Ashley needs to add to the tank is 300 - 190 = <<300-190=110>>110 gallons.
The time needed to fill the tank can be represented by the equation 5x = 110.
Dividing both sides of the equation by 5, we get x = 110/5 = <<110/5=22>>22 minutes. Answer: \boxed{22}.