how many solutions are there in N*N to the equation 1/x + 1/y = 1/1995 ?
Well, let me try again:
Attempt #2:
We observe that if x - 1995 is negative then y - 1995 will also be. But at least one of the factors has to less than -1995, giving us negative solutions, which we do not want.
Thus both x - 1995 and y - 1995 are positive.
Since we have 81 factors for 1995^2 ,we have 81 solutions for x,y.