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Can You Please Set This Up Algebraically?

Expert replies
by mkbigmoz » Fri Feb 13, 2009 5:42 pm
This is a simple question, but I had to reverse engineer the question to arrive at the solution. The "trading" part is throwing me off. Can someone please write the algebraic equation for this question? Thanks


"John and Mark each own a collection of baseball cards. The two collections combined contain 120 cards. If John were to trade 5 cards to Mark and Receive 2 of Mark's cards in return, John would have 22 more cards than Mark does. How many cards does Mark possess before the proposed trade?"



Here is how I set it up. Please let me know where I slipped.

1. J+M= 120 ~~~~~~~ J= 120-M

2. J-5+2= M-2+5+22

3. J-3= M+25

4. J= M+28

5. 120-M= M+28

6. 96= 2M

7. M= 46


Somehow the answer is 45. What went wrong?
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Source: — Problem Solving |

by Uri » Fri Feb 13, 2009 6:17 pm
the answer is wrong and you are correct. if you back-calculate, you can easily check that.
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by awesomeusername » Fri Feb 13, 2009 6:39 pm
Yes, I second that.

Mark 46
John 74

John -5 +2 = 71
Mark +5 -2 = 49
71 - 49 = 22
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by mkbigmoz » Sun Feb 15, 2009 4:21 pm
Ok. Well, Ill assume that the answer book is wrong. I was stuck on this problem for well over an hour, in an attempt to force the wrong answer :cry:
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