$-19\mathrm{.}5$Return $(\%)-19\mathrm{.}516\mathrm{.}417\mathrm{.}7-49\mathrm{.}743\mathrm{.}71\mathrm{.}8-16\mathrm{.}145\mathrm{.}944\mathrm{.}7-3\mathrm{.}7$ a$.$ What is the arithmetic average return over the$10-$year period? b$.$ What is the geometric average return over the$10-$year period? c$.$ If you invested$$ $$100$ at the$$ beginning, how much would you have at the$$ end?