Answer:
Debit balance is transaction amount minus margin: (250 × $36.55) − 0.46 × (250 × $36.55) = $4934.25
Equity is the margin amount, or 0.46 × (250 × $36.55) = $4203.25
Margin = (Value − Debit balance)/Value = [(250 × $46) − $4934.25] ÷ (250 × $46) = 57.09%.