So let's convert that into a sample 1000-person population. We'll stick with a strict gender binary as well, to simplify things a lot. And we'll assume a 50-50 gender split, again just to make the math easier.
So we have 500 women, 15 of whom are lesbians and 25 of whom are bi, and and 500 men, 15 gay and 25 bi. The other 460 men and 460 women are straight. 3/4