A clothing store buys shortsshorts for $$$$55\mathrm{.}0055\mathrm{.}00$ less $4040\%$ for buying over $50$ pairs, and less a further $28$ and two thirds$2823\%$ for buying last$$ season's style. The shortsshorts are then marked up to cover overhead expenses of $3838\%$ of cost and a profit of $26$ and two thirds $\%2623\%$ of cost$.($a$)$ What is the regular selling price of the shortsshorts$?($b$)$ What is the maximum amount of markdown to break$$ even? $($c$)$ What is the rate of markdown if the shortsshorts are sold at the$$ break$-$even price?