Find the coordinates of point S that lies along the directed line segment from R(-14,-1) to T(4,-13) and partition the segment in the ratio of 1:5

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?