In an engineering class that contained 50 students, the final exam consisted of 2 questions. Three fifths of the students answered the first question correctly. If four fifths of the remainder answered the second question correctly, how many students answered both questions incorrectly?  Select:  A) 4  B) 6  C) 10  D) 12  E) 24
1st Question : Three fifths of the students answered the first question correctly - so 3/5∗50=30   2nd Question : four fifths of the remainder answered the second question correctly so 4/5∗(50−30)=45∗20=16   total students who answered at least one Q correct =30+16= 
<gadget id="calculator">30+16</gadget>
<output>46</output>
46   so students who answered BOTH incorrectly= 50−46=4   4NSWER:4
<result>A</result>
In an engineering class that contained 50 students, the final exam consisted of 2 questions. Three fifths of the students answered the first question correctly. If four fifths of the remainder answered the second question correctly, how many students answered both questions incorrectly?