Multiplying both sides of an equation by the same number keeps the equation true. In this example, both sides are multiplied by 3, so the equation isn't changed.
The probability that a high school student in in the marching band is 0.47
so, 
The probability that a student plays a varsity sport is 0.32
so, 
the probability that a student is in the marching band and plays a varsity sport is 0.24
so, we get
P(M∩V)=0.24
a student plays a varsity sport if we know she is in the marching band
so,
P(V|M)=(P(V∩M))/(P(M))
now, we can plug values
and we get


So,
the probability that a student plays a varsity sport if we know she is in the marching band is 0.51063......Answer
The answer is 2-7=5 is the answer