Each year, the Department of Water Works measures the chloride concentration level in the water. The first year, they found the chloride concentration changed by −1.6 mg/L−1.6 mg/L . It is estimated that the chloride concentration will change −2.2 mg/L−2.2 mg/L the next year. What is the total change that will likely occur in 2 years? Enter your answer in the box.