Step 2: Split the equation into two equations, which can be the equation 1: 3(x+y)=2(2x-y), simplified to 5y-x = 0；; Equation 2: 2(2x-y)=6(x+y), which is simplified as -2x-2y= 12. These two equations form a system, and the answers are: x=-5, y=- 1.
(2) The reason is similar to (1), that is, multiply the common denominator first and then eliminate the denominator of the equation.
Question 2: x= 1, y =-2; X=- 1 and y=-4 are substituted into the equations respectively, and a set of equations is formed. After substitution, the equations are: k+b =-2; -k+b=-4, the solution is: k= 1, b=-3.
Question 3: Suppose Xiaoming voted for X and his father voted for Y, then we can list a set of equations: 3x=y, x+y=20, and the solution is x=5, y= 15.