A huge ice glacier in the Himalayas initially covered an area of 45 square kilometers. Because of changing weather patterns, this glacier begins to melt, and the area it covers begins to decrease exponentially. The relationship between A , the area of the glacier in square kilometers, and t tt, the number of years the glacier has been melting, is modeled by the following equation. A = 45 e − 0.05 t How many years will it take for the area of the glacier to decrease to 15 square kilometers? Give an exact answer expressed as a natural logarithm.