How many solutions (m,n positive integers only) are there for
floor(m/6)=floor(n/13) ?
List them.
For any integer x, the equation floor(m/6)=x has 6 integer solutions 6x+k where k=0 to 5. Similarly floor(n/13)=x has 13 integer solutions 13x+j where j=0 to 12.
Then the compound equation floor(m/6)=floor(n/13)=x has 6*13 = 78 solutions for every integer x.