Question

If 3/5 of the girls in class have long brown hair and 1/3 of them have green eyes how many girls in class have long brown hair and green eyes?

Answer 1

This is probabilistic "and". Knowing this you multiply the probabilities. So (3/5)*(1/3)=(3/15). 

Answer 2

I'm guessing 1/3 of 3/5 is what you mean

1/3 of 3/5=1/3 times 3/5=3/15=1/5

1/5 of class has long brown hair and green eyes