Question 447497
  <pre><font face = "Tohoma" size = 4 color = "indigo"><b> 
Hi
Arithmetic Series d = 3
6+9+12 ... +30
{{{a[n]=a[1]+(n-1)*d}}}
        6+(n-1)*3 = 30  |finding the correct number of terms
            3n = 27
             n = 9 

{{{S[n]=(n/2)(2*a[1]+ (n-1)d)}}}
{{{S[9]=(9/2)(2*6+ 8*3)}}} = (9/2) * 36 = 162