1. If there is water W and alcohol A, the topic is w = a, and the last water A * * * is given to B M, then A has water W–M, so A has alcohol W-(W-M) = M, and B has water M, so there is as much alcohol as B.

2. Almost, but I got S=40a=20b. There is an equation: S/(b-a)=40, and then 2a=b, so there is S=40a. Now find S/(b- 1.2a), that is, 40a/(2- 1.2a)=50 (days).

3. On the right, we find that the denominator is the same. We omit the denominator and discuss it in different categories:

(1). When the molecules on both sides are zero, it is easy to get x=-4 on the left and (A+B)X+2A+3B=0 on the right, so-2a = b.

(2) When the left and right molecules are not zero, the left is X+4 and the right is (A+B)X+2A+3B. Since left equals right, there are {A+B= 1, 2A+3B=4}, and the solution is {A=2, b =-65438+.

All in all, we have

When X=-2 or X=-3, the equation has no solution.

When X=-4, -2A=B (A and b are arbitrary real numbers).

When x is a real number other than -2, -3 and -4, {A=2, B=- 1}