Answer:
x=-3
Step-by-step explanation:
Boys:girls = 4/5
boys = 4/(4+5) = 4/9 of the class

after taking sqrt both side
3x/

3x/3y√2
x/√2y
multiply both denomenator and numerator by√2
√2x/2y
Answer is A
C = 2 pi r
but c = 15
15 = 2 pi r
15 = 2 * (22/7) * r
r = (15*7) / 2 / 22
r = 2.386