Could someone help me to do this one, Thanks!

1. Suppose an investor buys $100,000 of Apple Inc. using $50,000 of their own funds. The investor borrows the remaining $50,000 from their broker. The investor's broker has a maintenance margin of 25%. i. At the time of purchase, the investor's equity as a percentage is x%, find x: ii. Using the above the 25% maintenance margin, suppose that two weeks later, the value of the purchased securities falls to $60,000. what is the resulting fall in the investor's equity ? iii. If the maintenance margin falls below 25%, what is the least required margin call that the investor has to deposit