Answer: 9:11
Explanation:
Let x be the total number of students.
If 3/4 of students study a language That mean 3x/4 students study a language.
Number of students that don't study a language becomes
x - 3x/4 = x/4.
and 3/5 of those who study language study French, that means 3x/4 * 3/5 of students study French.
This gives 3x/4 * 3/5 = 9x/20 Studying French.
Number of students that study language but do not study French becomes
3x/4 - 9x/20 = 6x/20
Total number of students that do not study French becomes
[total number of students not studying any language] + [total number of students studying a language but do not study French ]
Which becomes
x/4 + 6x/20 = 11x/20
Hence ratio of those that study French to those that do not study French Becomes
9x/20 : 11x/20
9:11.