Short Sales

The maintenance margin is $30\%.$ Abby borrows $100$ IBM shares from her broker and sell them at

the price of $$30$ per share. The investor posts $$1\mathrm{.}8$K as collateral in her account with the broker.

$(15$ points$)$

$($a$)$ What is the margin of Abby$$s account?

$($b$)$ At what price will Abby receive a margin call?