In 1970, russian scientists began drilling a very deep bore- hole in the kola peninsula. their goal was to reach a depth of 15 kilometers, but high temperatures in the borehole forced them to stop in 1994 after reaching a depth of 12 kilometers. they found that below 3 kilometers the temperature t increased 2.5°c for each additional 100 meters of depth. (a) if the temperature at 3 kilometers is 30°c and x is the depth of the hole in kilometers, write an equation using x that will give the temperature t in the hole at any depth beyond 3 kilometers. (b) what would the temperature be at 12 kilometers? (c) at what depth (in kilometers) would they reach a tempera- ture of 200°c?