Posted by Spandita on .
There are 36 students in a student council in a school and the ratio of the number of boys to girls is 3:1 . How many more girls should be added to the council so that the ratio of boys to the number of girls may be 9:5

Math 
MathMate,
36 students
B:G = 3:1 = 27 : 9
Add x girls,
27/(9+x)=9/5
Solve for x by cross multiplication.