equations and inequalities.

A high-speed rail train travels at a constant speed through urban centers, then it accelerates when it reaches rural areas. The distance, D, for the high-speed rail train travelling at a constant speed is D = 240t. The distance travelled when it accelerates is given by D = 3(t - 2) + 3000. Solving this system of equations for t tells us: Select one: O a, the total time spent travelling Ob, the time the high-speed rail train travelled at a constant speed O c. the time when the high-speed rail train began to accelerate Od, the time the high-speed rail train spent accelerating