part a: –2°F > –6°F
part b: the inequality is representing the temperatures of city R and city S, comparing the difference in their temperatures.
part c: (marking city R at –2 on the number line and marking city S at –6 on the number line), using the number line to show the values of the city temperatures, city R is warmer because it is closer to 0 while city S is farther from zero and in the case that these are negative temperatures, the temperature closest to zero is the warmest.