There are 84 students in the glee club there are 12 more boys than girls what is the ratio of the number of girls to the number of boys

Let us denote the number of boys in the glee club with X and the number of girls with Y.
There are 84 students in the glee club, which means that the following equation can be written:
X+Y=84
We also now that there are 12 more boys than girls, so:
X=Y+12
We can rewrite the first equation like:
(Y+12)+Y=84
2Y+12=84
2Y=62
Y=62/2=31
X=31+12=43
So, the ratio of the number of girls to the number of boys is: Y/X=31/43