Hi, I'm new here I just started studying math again, because I want to go back to college and I don't remember any math from HS. I got a textbook, and it has the problem:

xy^2 - 6x - 2

x = 1/2 and y = -1/4.

I came to the answer of -5 + 1/32, and thought I was probably incorrect, but according to the book that answer is acceptable. Now, my issue lies here: it also listed another answer as correct: -159/32. For the life of me, I cannot understand where the 159 comes from. I'm completely lost. I'm sure its simple and I'll feel foolish after, but if anyone could go through and show me how to get -159/32?

Thanks in advance for helping<3