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Question 374862: sue took her collection of nickels and dimes to deposit in the bank. she has 7 fewer nickels than dimes. her total deposit was $46.70.how many dimes did she deposit?
Answer by nyc_function(2741)   (Show Source):
You can put this solution on YOUR website! Let n = nickels
Let d = dimes
We have a system of equations in two variables namely n and d.
Here is our system of equations:
5n + 10d = 4670
d = n - 7
NOTE: You can use any letter of choice to represent nickels and dimes but I thought it is more convenient to use n and d.
I multiplied all decimals by 100 for easy math work.
For example, 46.70 x 100 = 4670
A nickel = 0.05 and so, 0.05 x 100 = 5.
A dime = 0.10 and so, 0.10 x 100 = 10.
5n + 10d = 4670
d = n - 7
To find the number of dimes, we solve the equation d = n - 7 for n and then plug that into the other equation to find the number of dimes that Sue has in her collection.
d = n - 7...SOLVE FOR n
Simply add 7 to both sides and we're done solving for n.
d + 7 = n
We now plug that into 5n + 10d = 4670 and solve the equation for d.
Let n = (d + 7)
Understand?
5(d + 7) + 10d = 4670
5d + 35 + 10d = 4670
15d + 35 = 4670
15d = 4670 - 35
15d = 4635
d = 4635/15
d = 309
There are 309 dimes.
mrfeliz.webs.com
P.S. If I ask you, how many nickels does Sue have, what is the answer?
Think carefully....
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