Of the students at a certain high school, 90 percent took a course in arithmatic or geometry and 15 percent took courses in both. If the percent of students who took a course in arithmatic was 2 times the percent of students who took a course in geometry, what percent of the students took a course in arithmatic but not geometry?  Pick
A) 40%	B) 60%	C) 55%	D) 50%	E) 45%
You can also just use the formula   n(A or B) = n(A) + n(B) - n(A and B)   90 = 2X + X - 15   X = 35   2X = 70   This is the number of people who took arithmatic including those who took both. To get the number of people who took only arithmatic, 70 - 15 = 55%   Answer (55%)
<result>C</result>
Of the students at a certain high school, 90 percent took a course in arithmatic or geometry and 15 percent took courses in both. If the percent of students who took a course in arithmatic was 2 times the percent of students who took a course in geometry, what percent of the students took a course in arithmatic but not geometry?