To obtain the result:

Part 1: Calculate Margin Return:

Margin Return % = [((Ending Value  - Loan Payoff) / Beginning Equity Position) – 1] * 100 =

= [(([$24 × 1,000] – [$18 × 1,000 × 0.60]) /  ($18 × 0.40 × 1,000)) – 1] × 100 =

= 83.33%

Alternative (Check): Calculate the all cash return and multiply by the margin leverage factor.

                          = [(24,000 – 18,000)/18,000] × [1 / 0.40] = 33.33% × 2.5 = 83.33%

Part 2: Calculate Margin Call Price:

Since the investor is long (purchased the stock), the formula for the margin call price is:

          Margin Call = (original price) × (1 – initial margin) / (1 – maintenance margin)

   = $18 × (1 – 0.40) / (1 – 0.30) = $15.43