(1) The solutions of the two equations are the same, so x=3 and y=4. So at this time we need to solve two equations, 3m+4n=5 and 3n+4m=2.

12m+ 16n=20

12m+9n=6

Solution: m =-1; n=2 .

(2) Because the solutions of the two equations are the same, and they are both binary linear equations, only two unknown parameters are needed to get their solutions X, Y ... The equations are as follows.

2x- 3y= 15

x+y= 1

From this set of equations, we can find the solution.

Steps to solve application problems with column equations;

1, practical problems (review, find out all known and unknown conditions and quantitative relationships).

2. Set the last known number (usually direct and sometimes indirect), and use the algebraic expression of the last known number to represent all the last known quantities.

3. Find the equation relationship.

4. Solve the equation and find other unknowns.

5, test (test whether it is the solution of the original equation, whether it is in line with the practical significance).

6. answer.

Key point: review the questions. The key point is to use algebraic expressions of set unknowns to represent all unknowns and find equivalence relations.