If 85 percent of the test takers taking an old paper and pencil GMAT exam answered the first question on a given math section correctly, and 75 percent of the test takers answered the second question correctly, and 15 percent of the test takers answered neither question correctly, what percent answered both correctly? Choose the correct choice from the following options.
A) 60 %  B) 65 %  C) 70%  D) 75%  E) 80%
{Total} = {First correctly} + {Second correctly} - {Both correctly} + {Neither correctly}   100 = 85 + 75 - {Both correctly} + 15   {Both correctly} = 75.   Answer: 75%.
<result>D</result>
If 85 percent of the test takers taking an old paper and pencil GMAT exam answered the first question on a given math section correctly, and 75 percent of the test takers answered the second question correctly, and 15 percent of the test takers answered neither question correctly, what percent answered both correctly?