Question 1118234
If common difference d, then from index 4 to index 22 is {{{22-4=18}}} of these d.


Term at index 4 is 4.
{{{4+18d=5}}}
{{{18d=1}}}

{{{d=1/18}}}


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The general term of the progression is  {{{4+d*(n-1)}}} for common difference d and index n.  


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