2 5 of a class were boys and the rest were girls. Find the ratio of the number of boys to the number of girls in the class.

If 2 out of 5 is boys, then 5 - 2 = <<5-2=3>>3 is girls.

Hence, the ratio of the number of boys to the number of girls in the class is 2/3. Answer: \boxed{\frac{2}{3}}.