SOLUTION: Your piggy bank has 25 coins in it; some are quarters and some are nickels. You have $3.45. How many nickels do you have? (I know you can figure this out by trial and error, but yo

Algebra ->  Customizable Word Problem Solvers  -> Coins -> SOLUTION: Your piggy bank has 25 coins in it; some are quarters and some are nickels. You have $3.45. How many nickels do you have? (I know you can figure this out by trial and error, but yo      Log On

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Question 105150: Your piggy bank has 25 coins in it; some are quarters and some are nickels. You have $3.45. How many nickels do you have? (I know you can figure this out by trial and error, but you must write the equations and solve.)
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
"Your piggy bank has 25 coins in it; some are quarters and some are nickels."
First name your variables.
Q-quarters
N-nickels
1.Q%2BN=25
Each quarter has a value of $0.25.
Each nickel has a value of $0.05.
"You have $3.45."
0.25%2AQ%2B0.05%2AN=3.45
2.25Q%2B5N=345 Multiply both sides by 100 to get rid of the decimals.
Use equation 1 and come up with an expression for Q and use it in 2.
1.Q%2BN=25
Q%2BN-N=25-N
Q=25-N
Now substitute into 2.
2.25Q%2B5N=345
25%2825-N%29%2B5N=345
625-25N%2B5N=345
625-625-20N=345-625 Use the additive inverse of 625.
-20N=-280
-20N%2F%28-20%29=-280%2F%28-20%29 Use the multiplicative inverse of (-20).
N=14
Q=25-N
Q=25-14
Q=11
Check your answer
25Q%2B5N=345
25%2811%29%2B5%2814%29=345
275%2B70=345
345=345
Good answer.
11 quarters and 14 nickels in the piggy bank.