Answer :

[tex]the \ ratio \ is : \\ \\ boys \ to \ girls = 6:15= 2:5[/tex]

we know that

Ratio is the quantitative relation between two numbers

so

Let

x-------> number of boys in the class

y-------> number of girls in the class

[tex]ratio=\frac{x}{y}[/tex]

in this problem we have

[tex]x=6\ boys\\y=15\ girls[/tex]

Find the ratio

substitute the values in the formula

[tex]ratio=\frac{6}{15}[/tex]

Divide by [tex]3[/tex] both numerator and denominator

[tex]ratio=\frac{2}{5}[/tex]

therefore

the answer is

the ratio of boys to girls is [tex]\frac{2}{5}[/tex]