First we have to find the number of girls in the dance clamp, and if we know the total students and the number of boys we can calculate like this:
[tex]\begin{gathered} x+6=18 \\ x=18-6 \\ x=12 \end{gathered}[/tex]now the ratio of girls to the total number of students at the camp is:
[tex]\frac{12}{18}=\frac{6}{9}=\frac{2}{3}[/tex]So the ratio will be 2:3