Question 613269
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi, 
Note: {{{S[n]=(n/2)(2*a[1]+ (n-1)d)}}}
{{{S[6]= 654/3 =(2*a[1]+ 5d)}}}
{{{S[4]= 308/2 =(2*a[1]+ 3d)}}}***
  218 - 154 = 2d
         32 = d
   ***     154 = 2a[1] + 96
         29 = a[1]

   218 = 58 + 160