Tom, Mary and Sue each wrote an essay for their English class. Together, the three of them wrote a total of 650 pages. Mary and Sue wrote a total of 450 pages together, and Mary and Tom wrote a total of 350 pages together. How many pages did Mary write by herself? Select the correct option.
A) 200  B) 250  C) 150  D) 300  E) 350
Tom + Mary + Sue = 650 pages   Mary + Sue = 450 pages &lt;&lt; Plug this into the original formula to get Tom's total   Mary + Tom = 350 pages &lt;&lt; Plug this into the original formula to get Sue's total   (Mary + Sue) + Tom = 650 pages &gt;&gt; 450 + Tom = 650 &gt;&gt; Subtract 450 from each side &gt;&gt; Tom = 200   (Tom + Mary) + Sue = 650 pages &gt;&gt; 350 + Sue = 650 &gt;&gt; Subtract 350 from each side &gt;&gt; Sue = 300   Now plug in Tom &amp; Sue into the original formula.   200 + Mary + 300 = 650 &lt;&lt;Subtract 200 and 300 from each side   Mary = 150 pages   Answer: 150
<result>C</result>
Tom, Mary and Sue each wrote an essay for their English class. Together, the three of them wrote a total of 650 pages. Mary and Sue wrote a total of 450 pages together, and Mary and Tom wrote a total of 350 pages together. How many pages did Mary write by herself?