关于x,y得多项式（5m+1)x^2y+(4n-2)xy^2-3x+y-(-2m-6)x^2y+(3-3n)xy^2 不含三次项,求5m+2n的值关于x,y的多项式（5m+1)x^2y+(4n-2)xy^2-3x+y-(-2m-6)x^2y+(3-3n)xy^2 不含三次项,求5m+2n的值