SOLUTION: A bag contains 39 coins, all nickels and quarters. The total value of the coins in the bag is $6.35. How many of the coins are nickels?

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Question 1138560: A bag contains 39 coins, all nickels and quarters. The total value of the coins in the bag is $6.35. How many of the coins are nickels?
Answer by MathLover1(20850) About Me  (Show Source):
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A bag contains 39 coins, all nickels and quarters. The total value of the coins in the bag is $6.35. How many of the coins are nickels?
let nickels be n and quarters q
given:
n%2Bq=39....solve for n
n=39-q.........eq.1
the total value of the coins in the bag is $6.35

1n=$0.05
1q=$0.25
then, we have
0.05n%2B0.25q=6.35.....eq.2......substitute n from eq.1
0.05%2839-q%29%2B0.25q=6.35
1.95-0.05q%2B0.25q=6.35
-0.05q%2B0.25q=6.35-1.95
0.20q=4.40
q=4.40%2F0.20
q=44%2F2
q=22
go to n=39-q.........eq.1 substitute q
n=39-22
n=17
there are 17 nickels