Question 1074920: I need some help, I already got the equation but I'm stuck at the multiplying part. Here is the question: A person has only nickels and quarters. They have a total of $3.85 from 29 coins. Find the number of nickels and quarters. Please help me, I already got N+Q=29 and 5N+25Q=3.85, but I don't know what to do after that.
Found 3 solutions by rothauserc, KMST, MathTherapy:
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! 1) n + q = 29
2) 0.05n + 0.25q = 3.85
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Note total is 3 dollars and 85 cents so nickels and quarters use 0.05 and 0.25 respectively
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solve equation 1 for q
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q = 29 - n
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substitute for q in equation 2
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0.05n + 0.25(29 - n) = 3.85
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0.05n + 7.25 - 0.25n = 3.85
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-0.20n = -3.40
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n = 17
q = 29 - 17 = 12
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There are 17 nickels and 12 quarters
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check answer
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17(0.05) + 12(0.25) = 3.85
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0.85 + 3.00 = 3.85
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3.85 = 3.85
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our answers check
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Answer by KMST(5328)  (Show Source):
You can put this solution on YOUR website! It should be 5N+25Q=385 ,
because the 5, the 5N, the 25, and the 25Q represent,amounts in cents, not $.
ONE WAY:
After that you could solve the first equation for N,
and substitute the expression found into the other equation.
N=29-Q,
5(29-Q)+25Q=385
145-5Q+25Q=385
145+20Q=385
20Q=385-145
20Q=240
 --->
and  ---> .
That v way of solving a system of 2 linear equations with two variables is called substitution,
because you solve one equation for one variable,
and then substitute the expression found for the variable in the other equation.
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
I need some help, I already got the equation but I'm stuck at the multiplying part. Here is the question: A person has only nickels and quarters. They have a total of $3.85 from 29 coins. Find the number of nickels and quarters. Please help me, I already got N+Q=29 and 5N+25Q=3.85, but I don't know what to do after that.
For the value equation, if you're convert everything to cents, then it's 5N + 25Q = 385
If not, then it's: .05N + .25Q = 3.85
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