For $5 \leq 4k +1 \leq 29$, then find the maximum number of co-primes formed from the possible values of $k$.

ANS:$17$

This is a question from the Pearson IIT foundation series for grade 8 which I am unable to solve.

I tried solving it by trying to find numbers relatively prime to each other within the given parameters. But I am struggling with the fact that when I find numbers relatively prime to each other such as $6$ and $7$, how do I continue the list of relatively prime numbers. If I add $8$ and $9$ to the mix and I take off $6$, I can add two more at the expense of one number and have them relatively prime.But this is too tedious and I hope you have some trick I can apply. But I also don't understand how this is supposed to work in the context of K.

closed as off-topic by GNUSupporter 8964民主女神 地下教會, amWhy, Element118, José Carlos Santos, Paolo Leonetti Apr 14 at 18:12

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  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – GNUSupporter 8964民主女神 地下教會, amWhy, Element118, José Carlos Santos, Paolo Leonetti
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  • Coprime to what? $m$, $n$ or both? – rtybase Apr 14 at 10:01
  • Doesnt say.I re-worded the question for it to make sense. – Chirag M Apr 14 at 10:06
  • Your rewording doesn't make sense. Please edit the question to tell us the exact original wording, complete with necessary context. – Ethan Bolker Apr 14 at 17:09
  • So sorry,I reworded to show my approach.I hope it finally makes sense! – Chirag M Apr 15 at 10:01