If ∑an=S1\sum a_n = S_1∑an=S1 and ∑bn=S2\sum b_n = S_2∑bn=S2, what is ∑(kan+cbn)\sum (k a_n + c b_n)∑(kan+cbn)?
kS1+cS2k S_1 + c S_2kS1+cS2
kS2+cS1k S_2 + c S_1kS2+cS1
S1+S2S_1 + S_2S1+S2
k+ck + ck+c