$8,153 + $847 = $9000 money deposited in bank account)
$9000 / 100 = $90 (used to buy 100 cameras, $90 each)
$150 - $90 = $60 (each camera sold and earned $60)
$60 * 100 = $600 (total earned when sold 100 camera)
answer:
Tom earned $60 from selling each camera