The consulting agency has been tracking the cost of water and sewer services provided to residents in an area. They found when the price for water and sewer services was $70 per month to these residential customers, demand for water was 60 gallons per day. When they priced the water and sewer services higher at $80 per month, their residential customers reduced demand to 55 gallons per day.

What is the price elasticity for the water and sewer services?