At a certain pizzeria,~$1 \over 8$~of the pizzas sold in one week were mushroom and ~$1 \over 3$~ of the remaining pizzas sold were pepperoni. If n of the pizzas sold were pepperoni, how many were mushroom?

~$3 \over 8$~n

~$3 \over 7$~n

~$7 \over 16$~n

~$7 \over 8$~n

3n