4/15 of the 315 members of a book club are male. how many female members are there in the club?

84 members out of 315 members are male.

315 - 84 = 231 members

231 members are female.

If you're wondering how they got their answer this is how,

First we need to find out 4/15 of 315 (How the heck do we do that??)
Easy like this :)

(4 ÷ 15) x 315= 84

so now we need to subtract the males from the rest of the people (like this!!)

315 - 84 (males) = 231

So since the only other gender is female we now know that the rest of the people are females, meaning that there are 231 females!! 

:) 231 females are at the club! I hope this helped!

If you make it a little more clear i can answer it