In the graph, the area below f(x) is shaded and labeled a, the area below g(x) is shaded and labeled b, and the area where f(x) and g(x) have shading in common is labeled ab. y< -2x +6 y< x +

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?