# Math Help - 20 Hard SAT questions from the official guide.

1. ## 20 Hard SAT questions from the official guide.

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 n and p are integers greater than 1 and if p is a factor of both n+3 and n+10, what is the value of p?

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.

2. 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.
we know that $2x+z=2y$

rewrite the 2nd equation as

$2x+2y+z=20 \iff 2x+z+2y=20 \iff \underbrace{2y}_{2x+z}+2y=20$

$4y=20 \iff y=5$

3. Omg. Thanks so much! Can I PM you for more help?

4. Originally Posted by Potterpie
Omg. Thanks so much! Can I PM you for more help?
Please post your questions in the forum. There are many people here that can help you, and most are much "smerter" than I.

P.S. I did mean Smerter "It is more prestigious than smarter" quoting Jen

5. allrighty. =)

I posted the next question I have in my first post.

6. 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 n and p are integers greater than 1 and if p is a factor of both n+3 and n+10, what is the value of p?

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.
Ok so you know p divides both n+3 and n+10. That also means that p divides the difference between n+3 and n+10, which is 7. So p must be equal to 7, since p is prime and greater than 1.