Hello board. I'm trying to solve the problems on the accuplacer practice exam online and am having trouble with one of the questions. It is:

What is the value of the expression 2x² + 3xy – 4y² when x = 2 and y = - 4?

The answer I keep coming up with is -4. The only choices are -80, 80, -32, and 32.

What am I doing wrong?