An arithmetic sequence is given by the rule $\displaystyle {L}{\left({n}\right)}={5}+{15}{n}$.

Find the sum of these terms $\displaystyle {L}_{{100}}+{L}_{{101}}+{L}_{{102}}+\ldots+{L}_{{2099}}$

sum =

Hint: What is the sum of all the terms from $\displaystyle {n}={0}$ to $\displaystyle {n}={2099}$? Now, what is the sum of the first 100 terms?