Originally Posted by

**Potterpie** I'm a freshman in high school and I'm taking a SAT prep course my district is offering. We have workbooks and stuff and we have the Official SAT Study Guide, that monstrous, huge, book. I went through the whole math section (because my score is only a 550) and picked out the questions labeled "hard" so I could have a better understanding.

I worked through all of them and I have **20**, no exaggeration, that I absolutely cannot understand.

Here's an example.

If 2x+z=2y and 2x+2y+z=20, what is the value of y?

I've tried setting up a matrix, but I get an error message when I try to solve. I've solved for y and graphed. I've double checked. The answer is supposed to be 5, but how am I supposed to get that?

I've tried calling my teacher (who gave us his cell phone number), but he didn't answer. I would ask my math teacher, but he doesn't tutor on the day I would have to go.

If you think you can help me, you really good math people, please reply.