First, divide it by something you know for sure that works, in this case, let's say 5 because the number ends in 5 or 0. Now divide it by 5, and you will get 15. 15 is the product of 3 and 5. So now list all the numbers that you divided: 3, 5, and 5. All three of them are prime, and 3*5*5 is 75. Therefore the answer is 3*5*5
