sum of 1 n = 20/ r = 1
It would help if you could clarify your expression.
If construed as a number theory problem, the best that I could come up with
sum of 1 to n = r(r+1) sum of 1 to 3 = 2*3 etc.
sum of 1 to n = 20/r sum of 1 to 4 = 20/2
So r = 2
If I understand you correctly, you are summing the integers from 1 to n.
This sum is n(n+1)/2. I have no idea what you mean by r.
This topic made me laugh for some reason.
I viewed it as two diophantine equations in two variables
n(n+2)/2 = r(r+1) and m(m+1)/2 = 20/r for which the only solution is n = 3, m =4, r = 2
I did not use the formula n(n+1)/2 since I knew the values of n(3) and n(4) already.
No certainty that I understood the problem correctly though I don't see how there could be a different problem intended.
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