how do I find all real pairs of a,b such that (80+b)/(10a+b) is an integer? I tried using the Euclidean algorithm and I ran it with 80+b and 10a+b once assuming 80+b>10a+b but then I didn't know what to do.
So how should I do this problem?
@bobjeff123 Rather than working on the Euclidean algorithm as it might get messy with two variables, where does this problem come from? This will form the context of the question which makes it easier for us to answer.
so the question comes indirectly from crossword from a competition, and when I read the answer for the crossword it seemed to have used trial and error which I thought was inefficient so I set up an equation for it
I actually get how to solve the crossword, it was just that small obstacle and technically I could use trial and error like the solution but I'm more interested in how to find a solution for that equation I just came across. The crossword is sort of just random inspiration, it's also from a UK competition which I don't think expects you to know the theory to solve this problem.
I apologize for butting in, but it would be best if you could post a picture of all the relevant parts. Please also make sure that the problem is not part of an ongoing competition ( I am saying this because you mentioned a competition).
do I post a picture of the crossword itself? Because I'm just saying I got inspiration for the question from that crossword however I don't really need to solve it
basically the number 5 tile can either be 8,5 or 2 but I'm just assuming its 8, and then Im setting the tile on the right to be "b" and the tile on the 4 to be "a". So I basically get 10a+b has to be a proper factor of 80+b so thats how I was inspired.
"The XY problem is asking about your attempted solution rather than your actual problem.
That is, you are trying to solve problem X, and you think solution Y would work, but instead of asking about X when you run into trouble, you ask about Y."
I just fell like talking too much about the origins/crossword may digress the question off topic as the solution is actually a bit long - after all equation is the main question here, should I instead mention what was going through my thought process when solving the problem so that people can understand my logical reasoning better?
I have the solution for the crossword only, in fact in an attempt to turn brute-force into efficiency, I feel as if it has turned into an overcomplication. But a good overcomplication; which was turned into an interesting problem for myself