1/3m（x-n）=1/4（x+2m）1/3mx-1/3mn=1/4x+1/2m同时乘以12，得4mx-4mn=3x+6m(4m-3)x=6m+4mnx=(6m+4mn)/(4m-3)
1/3m（x-n）=1/4（x+2m）两边乘以124m(x-n)=3(x+2m)4mx-4mn=3x+6m4mx-3x=4mn+6m(4m-3)x=4mn+6mx=(4mn+6m)/(4m-3)
