Answer: it will take 41 nights for the points he earns with either hotel to be the same.
Explanation:
Let x represent the number of nights that it will take for the points he earns with either hotel will be the same.
Hotel Elegance is currently offering 525 points for signing up, plus 35 points for every night Alec books at the hotel. This means that the number of points that Alec will get of he spends x nights at the hotel is
35x + 525
Alternatively, Hotel Paradiso is offering a sign-up bonus of 402 points, plus 38 points per night. This means that the number of points that Alec will get of he spends x nights at the hotel is
38x + 402
For the points to be the same at either hotels, the number of nights would be
35x + 525 = 38x + 402
38x - 35x = 525 - 402
3x = 123
x = 123/3 = 41