SOLUTION: A bank teller had 125 $10 and $5 bills to start a day. If the total value of the bills was $1000 how many $5 bills did he have?

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Question 756309: A bank teller had 125 $10 and $5 bills to start a day. If the total value of the bills was $1000 how many $5 bills did he have?
Found 2 solutions by Cromlix, Edwin McCravy:
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
$10 bills = x
$5 bills = y
x + y = 125.....1
10x + 5y = 1000....2
Multiply (1) by 5
5x + 5y = 625.....3
10x + 5y = 1000....2
Subtract (3) from (2)
5x = 375
x = 75
Substitute x = 75 into Eq (1)
x + y = 125
75 + y = 125
y = 125 - 75
y = 50
Therefore the teller has:
75 $10 bills and 50 $5 bills.
Proof
75*$10 + 50*$5 = $1000
Hope this helps
:-)

Answer by Edwin McCravy(20059) About Me  (Show Source):
You can put this solution on YOUR website!
Without algebra (you can do it in your head this way):

If he had only $5 bills he would have 1000÷5 or 200 bills.  But since
he had only 125 bills, then 200-125 or 75 of them had to be worth twice 
as much as a $5.  So he had 75 tens and 125-75 = 50 fives. 

With algebra  (which is the way your teacher wants you to do it)

The other tutor used two unknowns, but it can be done with only 1 unknown.

Let x = the number of $5 bills.
Then the number of $10 is 125-x

So

            %28matrix%286%2C1%2C%0D%0A%22%245%22%2CTIMES%2CTHE%2CNUMBER%2COF%2CFIVES%29%29%22%22%2B%22%22%28matrix%286%2C1%2C%0D%0A%22%2410%22%2CTIMES%2CTHE%2CNUMBER%2COF%2CTENS%29%29%22%22=%22%22%28matrix%285%2C1%2C%0D%0ATHE%2CTOTAL%2CAMOUNT%2COF%2CMONEY%29%29

            5·x + 10·(125-x) = 1000
             5x + 1250 - 10x = 1000
                         -5x = -250
                           x = 50

Edwin