In the solution, it states that 59 and 45 have a difference of 7. This is clearly wrong. It should have stated "For choice ii.), 59 and 45 have a difference of 14, which is a multiple of 7, so this is the correct answer."
In week 3's challenge question 19, I am not sure if this is a mistake. The answer, you say, is the number of multiples of three between 1 and 100. But if we take x=3, 3 and 0 cannot have the status of being relatively prime or not because 0 isn't defined to be (not) relatively prime to any number, according to Google searching afterward. So the answer should be 33-1, or 32. Can someone clear things up for me? Thanks a lot.
