<PRE><B>Question 124107</B>
Kim has $210 in $5 bills and $20 bills. She has a total of 24 bills. How many $5 bills and how many $20 bills does she have? 
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Let x = no. of $5 bills
Let y = no. of $20 bills
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Write an equation for each statement:
&quot;Kim has $210 in $5 bills and $20 bills.&quot;
 5x + 20y = 210
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&quot;She has a total of 24 bills.&quot;
  x + y = 24
  x = (24 - y) subtracted y from both sides, we are going to use this for substitution in the 1st equation
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 How many $5 bills and how many $20 bills does she have?
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Using this equation; 5x + 20y = 210, substitute (24-y) for x, solve for y
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5(24-y) + 20y = 210
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120 - 5y + 20y = 210; multiplied what&#39;s inside the brackets
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-5y + 20y = 210 - 120; subtracted 120 from both sides
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15y = 90
y = {{{90/15}}}; divided both sides by 15
y = 6 ea $20 bills 
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We know x = 24 - y; substitute 6 for y
x = 24 - 6
x = 18 ea $5 bills
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Check our solution in the $equation
18(5) + 6(20) = 
90 + 120 = 210; confirms our solution
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