Hello! @authenticcrane
I'm not sure if the challenge was wrong or not, but I have previously done this question before and it seems I got the same answer as yours. I belive there is no problem in your solution though.

@debbie

How do we know that the two horizontal lines are parallel? They looked parallel but the question does not tell us it is.

@Meth Woah! Amazing!

@intelligentspider
oh, ok. thx

@thoughtfulmongoose
I think the reason for this is because when you take the smaller one from each line (62 to 25) and add the remaining (24-1) the subset becomes {1,2,...62}, hence the 62.

@RZ923 LOL HHHHHH 😁

@RZ923 QUITE TRUE

@versatilemole i could give as many solutions as i can to this problem, and then people can add on solutions and count how many ways we can make 100.

Not really 🙂 Notice how Elmo has three blocks. It wouldn't be $$\binom{9}{3}$$ because you use a separate block every time so you would have to choose the first block, then the second, and so on. Try to see where you can go from there 😉

Note: Sorry this is so late I doubt you're active on this forum anymore.