1. Suppose his plane ticket is X yuan, then according to the meaning of the question: (30-20) * x *1.5% =120, and x=800 yuan, then his plane ticket is 800 yuan. 2. Suppose there are X 8.25m water pipes, then there are (100-x) 6.25m water pipes. According to the meaning of the question, 8.25*x+6.25*( 100-x)=695, and 8.25m water pipes have x=35 (root). 3. Suppose the team wins X games and the team draws (14-x-5). According to the meaning of the question, it is: 3 * x+1* (14-x-5) *1+5 * 0 = 65438. 4. Assuming that the speed of A is xkm/h, then the sum of the speeds of two people is 28/3.5=8km/h, and we can get that the speed of B is (8-x)km/h, and then we can get the question: 2*x+8*2=30, and we can get x=7(km/h), so the speed of A. B = A+C B-C = 2( 100 C+ 10 B+A)-( 100 A+ 10 B+C)=。