# Algebra problem, dvds

• Jul 27th 2012, 12:18 PM
Sewilliams13
Algebra problem, dvds
Phil has three times as many DVDS as sam has. Even after Phil gives Sam 6 DVDs, he still has 16 more DVDs than Sam has. What was the original number of DVDs that Phil had?
I set this up like so,
P=3*S
P-6=16+S+6

(S=Sam)
How do I solve this? Any answers appreciated!(Worried)
• Jul 27th 2012, 12:32 PM
HallsofIvy
Re: Algebra problem, dvds
Quote:

Originally Posted by Sewilliams13
Phil has three times as many DVDS as sam has. Even after Phil gives Sam 6 DVDs, he still has 16 more DVDs than Sam has. What was the original number of DVDs that Phil had?
I set this up like so,
P=3*S
P-6=16+S+6

(S=Sam)
How do I solve this? Any answers appreciated!(Worried)

Looks good. Now, since P= 3S, you can replace P in the second equation 3S: 3S- 6= 16+ S+ 6= S+ (16+ 6)= S+ 22.
If you add 6 to both sides, that gives you 3S- 6+ 6= S+ 22+ 6 or 3S= S+ 28. Can you finish that?
• Jul 27th 2012, 01:04 PM
Sewilliams13
Re: Algebra problem, dvds
Quote:

Originally Posted by HallsofIvy
Looks good. Now, since P= 3S, you can replace P in the second equation 3S: 3S- 6= 16+ S+ 6= S+ (16+ 6)= S+ 22.
If you add 6 to both sides, that gives you 3S- 6+ 6= S+ 22+ 6 or 3S= S+ 28. Can you finish that?

I can finish that, to end up getting 14=s. Thank you very much! What a simple blunder-_- All that frustration for nothing! My SAT book gave this strategy, which threw me off.
P=3S P/3=S
P-6=16+P/3+6
P-6=48+P+18/3
3P-18=48+P+18
2P=84
P=42.

^^The book (Grubers 2013) Is trying to say that this is a simpler strategy. I disagree. Thanks for the wonderful help!
• Jul 27th 2012, 07:48 PM
Wilmer
Re: Algebra problem, dvds
Quote:

Originally Posted by Sewilliams13
I can finish that, to end up getting 14=s. Thank you very much! What a simple blunder-_- All that frustration for nothing! My SAT book gave this strategy, which threw me off.
P=3S P/3=S
P-6=16+P/3+6
P-6=48+P+18/3
3P-18=48+P+18
2P=84
P=42.
^^The book (Grubers 2013) Is trying to say that this is a simpler strategy. I disagree. Thanks for the wonderful help!

Well, it is simpler....since you're asked how many DVD's Phil has (not S); solution leads directly to Phil;
doing it the other way leads to DVD's Sam has; you then need to substitute to get Phil.

Btw, this: P-6=48+P+18/3
requires brackets: P-6=(48+P+18)/3
• Jul 28th 2012, 08:35 AM
Sewilliams13
Re: Algebra problem, dvds
Ahh that makes so much more sense with brackets!(they were not in the book ?) Thank you!!