Answer and Explanation:
The computation is shown below:
For Tom, without margin is
= Number of shares × (price after eight months - purchased value) ÷ ( number of shares × purchased value)
= (100 × ($40 - $43) ÷ (100 × $43)
= -6.98%
For sam, with margin is
= Number of shares × (price after eight months - purchased value) ÷ ( number of shares × purchased value × initial margin requirement )
= (100 × ($40 - $43) ÷ (100 × $43 × 60)
= -11.63%