2mn-5m=3n+25
n*(2m-3)=5*(m+5)
n=2.5*(2m+10)/(2m-3)=5*(1+13/(2m-3))/2
因为n为正整数,所以1+13/(2m-3)为正偶数,13/(2m-3)为正奇数,又因为13是质数,
所以13/(2m-3)=1或13
=1时,m=8,n=5
=13时,m=2,n=35