John wants to buy shares of ABC Co$.$ stock. The stock is currently trading at $$50$ per share. He currently has $$3,000$ of cash in his account. He plans to buy stock on margin. This broker sets a minimum maintenance margin of $40\%.$

a$.$ If his margin is going to be $60\%,$ how many shares of stock will he buy?

b$.$ The next day, before the market opens, ABC Co$.$ announces that they are being sued. At $9$:$30$ a$.$m$.,$ the market opens, and the stock drops to $$33.$ How much is John's margin $\%$ now?

c$.$ Based on the calculations in Part B$,$ state if there will be a margin call.