In a test, sixty percent students passed in Maths and 65% in History, 40% passed in both of these subjects. If 90 students failed in maths and history both, then what is the total number of students? Pick.
A) 600	B) 650	C) 700	D) 750	E) None of these
Explanation :   Solution: let the total number of students be x.   Number passed in one or both is given by : n( A U B) = n(A)+n(B) -n( A ^ B).   = 60% of x+65% of x-40% of x   = (60/100 * x + 65/100 * x - 40/100 * x)   = 85x/100 = 17x/20.   Failed in both = (x - 17x/20) = 3x/20.   .'. 3x/20 =90   x = 90*20/3= 
<gadget id="calculator">90*20/3</gadget>
<output>600</output>
600.   600nswer : 600
<result>A</result>
In a test, sixty percent students passed in Maths and 65% in History, 40% passed in both of these subjects. If 90 students failed in maths and history both, then what is the total number of students?