(1) According to the function image, the distance between A and B is 900 kilometers, so the answer is 900; ∴C(6 2) From the meaning of the question, it is concluded that the speed of the authorities is 900÷ 12=75 km/h, the speed of the express train+local speed =900÷4=225 km/h, and the express train = 225-75 =150 km. 450). Let yCD=kx+b(k≠0, k and b are constants). Substitute (6450) and (12900) into yCD=kx+b, with 12k+b = 9006k+b. (3) According to the meaning of the question, 4.5-(900-4.5× 75) ÷/.