Answer
$$\sum\limits_{i = 1}^{20} {\left( {4i + 6} \right)} $$
Work Step by Step
$$\eqalign{
& 10 + 14 + 18 + \cdots 86 \cr
& {\text{Calculating }}d{\text{ or }}r \cr
& 14 - 10 = 4 \cr
& 18 - 14 = 4 \cr
& {\text{This is an arithmetic series with }}{a_1} = 10{\text{ and }}d = 4 \cr
& {\text{The general term is }} \cr
& {a_n} = {a_1} + \left( {n - 1} \right)d \cr
& {a_n} = 10 + \left( {n - 1} \right)\left( 4 \right) \cr
& {a_n} = 10 + 4n - 4 \cr
& {a_n} = 4n + 6 \cr
& {\text{The last term is }}86,{\text{ then}} \cr
& 86 = 4n + 6 \cr
& 80 = 4n \cr
& n = 20 \cr
& {\text{The sum of notation can be written as}} \cr
& \sum\limits_{i = 1}^{20} {\left( {4i + 6} \right)} \cr} $$
