I think in the question (2), there should be one more constraint that x/n, y/n+1 and z/n+2 are all integers. In this case, 30/n is an integer. So, the possible values of n are 1, 2, 3, 5, 6, 10, 15. So is 7.

I think in the question (2), there should be one more constraint that x/n, y/n+1 and z/n+2 are all integers. In this case, 30/n is an integer. So, the possible values of n are 1, 2, 3, 5, 6, 10, 15. So is 7.