Of the students at a certain high school, 90 percent took a course in algebra or geometry and 10 percent took courses in both. If the percent of students who took a course in algebra was 3 times the percent of students who took a course in geometry, what percent of the students took a course in algebra but not geometry?	Choose the correct choice:
A) 35%
B) 45%
C) 55%
D) 65%
E) 70%
You can also just use the formula   n(A or B) = n(A) + n(B) - n(A and B)   90 = 3X + X - 10   X = 25   3X = 75   This is the number of people who took algebra including those who took both. To get the number of people who took only algebra, 75 - 10 = 65%   Answer (65%)
<result>D</result>
Of the students at a certain high school, 90 percent took a course in algebra or geometry and 10 percent took courses in both. If the percent of students who took a course in algebra was 3 times the percent of students who took a course in geometry, what percent of the students took a course in algebra but not geometry?