Question 998451

the fifth abd fifteenth term of an AP is 13 and 17 .find the sum of first 21 term
<pre>Are you sure this is the problem?
If so, it involves a lot of fractions/decimals
You should get: Common difference, or {{{highlight(d = 2/5)}}} 
You should get: First term, or {{{highlight(system(a[1] = (57/5)_OR,11&2/5))}}} 
You should get: Sum of first 21 terms, or {{{highlight_green(system(S[21] = (1617/5)_OR,323&2/5))}}}