step by step would be appreciated thanks

In reality, when you purchase stocks, you can borrow part of the purchase price of the stock from a broker. However, you are not allowed to borrow an arbitrarily large amount. The maximum amount you can borrow initially is dictated by the following margin requirement: you must have equity in your account that is at least worth 50% of the value of the shares you purchase. Margin = Equity/Value of stocks you purchase 50% margin is the initial margin requirement. In addition to the initial margin requirement, there is a maintenance margin requirement: your margin should always be maintained above 25% level. The XYZ stock is currently traded at $15 per share. Suppose you have $20,000 cash available, how many shares of XYZ stock can you buy if you borrow the maximum amount from the broker under the above margin requirements? Suppose you purchased the maximum amount of XYZ stock using the margin trade described in part (a), what is the minimum price of XYZ one year from now for which your portfolio still satisfies the maintenance margin requirement