Let $a\equiv (3^{-1} 5^{-1} 7^{-1})^{-1}\pmod{11}$. What is the remainder when $a$ is divided by $11$

Fanny mendelssohn manages all the magazines and paperback books at a local grocery store. she prices many paperbacks to sell at $7.99. the cost to the store is $5.29. what is the markup rate on a paperback book, based on its cost?

Nikita wants to apply for student aid to fund her college education. arrange the steps involved in nikita’s application for financial aid

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.