1. Solve the following fractional equation:

1、

2、

Second, simplify first and then evaluate:

Third, the column fractional equation to solve application problems:

1.Group A and Group B students went to the nursing home 4.5 kilometers away from the school to clean up. After walking for half an hour, the students in Group B started to ride bicycles. Results Two groups of students went to the nursing home at the same time. If the speed of walking is the speed of cycling, what are the speeds of walking and cycling?

2. The numerator of the fraction is 6 less than the denominator. If 1 is added to both the numerator and denominator, the score is equal to. Find this score.

Fourth, the calculation questions:

1. If 3x+2y-z = 14, find the values of x, y, z, y and z. 。

2. It is known that three positive numbers A, B and C satisfy abc= 1, and the calculated value. 1, I sent it to you by Baidu hi, 2,12/(m2-9)+2/3-MX+2-4/(2-a).

2. If the equation 1/x- 1=2/x-a has a positive integer solution, find the value of a. ..

3. The distance between Party A and Party B is 48km, and the time for the ship to travel from Party A to Party B is equal to half the time for the ship to travel in the opposite direction. Given the current speed of 4 km/h, find the ship speed in still water.

4.{x^2-y^2/xy}^2÷(x=y)*{x/x-y}...,0,