SOLUTION: Good evening, I'm having some trouble assisting my son (8th grade) with his math homework. The problem states: Write and solve a system of equations that represents each sit

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Question 705999: Good evening,
I'm having some trouble assisting my son (8th grade) with his math homework.
The problem states:
Write and solve a system of equations that represents each situation. Interpret the solution.
Neil has a total of twelve $5 and $10 bills in his wallet.He has 5 times as many $10 bills as $5 dollar bills. How many of each does he have?
Any help is greatly appreciated!!! Thanks in advance!!! Susan

Found 2 solutions by nerdybill, josmiceli:
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Neil has a total of twelve $5 and $10 bills in his wallet.He has 5 times as many $10 bills as $5 dollar bills. How many of each does he have?
.
Let x = number of $5 bills
then from "Neil has a total of twelve" we have
12-x = number of $10 bills
.
From: "He has 5 times as many $10 bills as $5 dollar bills." we get our equation:
x = (1/5)(12-x)
multiplying both sides by 5:
5x = 12-x
6x = 12
x = 2 (number of $5 bills)
.
Number of $10 bills:
12-x = 12-2 = 10

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = the number of $5 bills he has
Let +b+ = the number of $10 bills he has
given:
(1) +a+%2B+b+=+12+
(2) +b+=+5a+
-------------
Substitute (2) into (1)
(1) +a+%2B+b+=+12+
(1) +a+%2B+5a+=+12+
(1) +6a+=+12+
(1) +a+=+2+
and, since
(2) +b+=+5a+
(2) +b+=+5%2A2+
(2) +b+=+10+
The number of $5 bills he has is 2
The number of $10 bills he has is 10
----------------
Notice that this is not really a "money" problem.
You could replace $5 bills with blue marbles
and $10 bills with red marbles, and you have
the same problem.