Why does interacting in sexual intercourse feel so good?

Because human beings are hard-wired to make more human beings.

At one time, there were people who didn't especially like it, and didn't
really care whether they ever did it or not.  They produced far fewer
children than the people who would do almost anything for the chance
to do it, and it didn't take long before there were no more of the ones
who didn't care.

The purpose of a lab is to do your "expirements" the importance of the topic is so you can now what the story is about and the last one is because no one is me with my question ( what is 3 over 4 x - 9 = 27 maybe you can )