Okay, here we have this:
We know that 39 of the 90 students in the band are male this means that the rest are women, let's calculate how many they are:
Womens=Total-Male
Womens=90-39
Womens=51
Now, knowing this we are going to find the ratio of female to male students in the band:
Number of female/ Number of male = 51/39
Now, let's convert it in lowest terms:
Ratio=51/39=17 female/13 male
Finally we obtain that there are 17 female for each 13 male.
