A sum of money lent out at S.I. amounts to a total of $600 after 2 years and to $850 after a further period of 5 years. What was the initial sum of money that was invested?	Choices.
A) $500 B) $520 C) $540 D) $560 E) $580
S.I for 5 years = $850 - $600 = $250   The S.I. is $50/year   S.I. for 2 years 850 -  600= 
<gadget id="calculator">850 -  600</gadget>
<output>250</output>
$250   The S.I. is $50/year   S.I. for 2 years= $100   Principal = $600 - $100 = $500   The answer is $500.600 -  100= 
<gadget id="calculator">600 -  100</gadget>
<output>500</output>
$500   The answer is $500.
<result>A</result>
A sum of money lent out at S.I. amounts to a total of $600 after 2 years and to $850 after a further period of 5 years. What was the initial sum of money that was invested?