Hank has thirteen coins in his piggy bank. Some of the coins are quarters, some are nickels, and he has a total of $3.30. Which system of equations can be used to determine how many quarters, x, and how many nickels, y, he has?
x + y = 13
0.25x + 0.05y = 3.3

x + y = 13
0.25x + 0.5y = 3.3

x + y = 3.3
0.25x + 0.05y = 13

x + y = 13
25x + 5y = 3.3

Question

Hank has thirteen coins in his piggy bank. Some of the coins are quarters, some are nickels, and he has a total of $3.30. Which system of equations can be used to determine how many quarters, x, and how many nickels, y, he has?
  x + y = 13
  0.25x + 0.05y = 3.3

  x + y = 13
  0.25x + 0.5y = 3.3

  x + y = 3.3
  0.25x + 0.05y = 13

  x + y = 13
  25x + 5y = 3.3

anonymous · Answer

Let's represent quarters as x, and nickels as y
there are 13 nickels and quarters combined, so you can create the equation x + y = 13.  This is the first equation in the system of equations

anonymous · Answer

Next, you know that a quarter is 0.25 out of a dollar, and a nickel is 0.05 of a dollar.  Since there is a total of 3.3 dollars, you can create the equation 0.25x + 0.05y = 3.3.  
That is the second equation of the system of equations.

anonymous · Answer

So when you look at the answer choices, you can see that the choice that contains both of those equations is the first one.

anonymous · Answer

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