Question 10: Let the distance between cities A and B be x kilometers. We can get x/ 100+x/80+ 1/2=5 from the question, and we can get x=200.

1 1 Question: (1) See you after x hours of departure. From the meaning of the question, we get that X = 2.8:60x+ 100 X = 448.

(2) Assuming that the two cars meet after the express train leaves X hours, x=2.6 is obtained from the question meaning of 60*32/60+60x+ 100x=448.

Question 12: Suppose A meets B after X hours of departure, and get X = 4/5 (X+1)/3+X/2 =1from the meaning of the question.