If 75 percent of a class answered the first question on a certain test correctly, 30 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly?	Select.
A) 25%
B) (8) 20%
C) 30%
D) 50%
E) 65%
I didn't understand how to connect 20 percent with the whole equation.   Why 20 is out of the percentile diagram (circles) but inside of 100?   20% appeared in the exam; however did not answer Question AQuestion B correctly   So they are out of the two circles, however as they have appeared in the exam, they have to be taken into consideration for calculation purpose   I am doing it this way:   Suppose the total class size is 100, then 20 percent of the class answered incorrectly and rest 80 percent answered correctly in question 1 or 2 or both.   Now,   100 - [(75 - x) + x + (30 - x)] = 20 .......... values are in percent   x = 20 - 100 + 105= 
<gadget id="calculator">20 - 100 + 105</gadget>
<output>25</output>
25   25%ns: 25%
<result>A</result>
If 75 percent of a class answered the first question on a certain test correctly, 30 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly?