Of the students at a certain high school, 90 percent took a course in algebra or geometry and 18 percent took courses in both. If the percent of students who took a course in algebra was 2 times the percent of students who took a course in geometry, what percent of the students took a course in algebra but not geometry? Pick
A) 72% B) 70% C) 65% D) 60% E) 54%
You can also just use the formula   n(A or B) = n(A) + n(B) - n(A and B)   90 = 2X + X - 18   X = 36   2X = 72   This is the number of people who took algebra including those who took both. To get the number of people who took only algebra, 72 - 18 = 54%   Answer (54%)
<result>E</result>
Of the students at a certain high school, 90 percent took a course in algebra or geometry and 18 percent took courses in both. If the percent of students who took a course in algebra was 2 times the percent of students who took a course in geometry, what percent of the students took a course in algebra but not geometry?