document.write( "Question 1082722: systems of equations: Larry has $4 in nickels and quarters. If there are 36 coins in all, how many nickels and how many quarters does Larry have. \n" ); document.write( "
Algebra.Com's Answer #696792 by My Virtual Math Guide(2) You can put this solution on YOUR website! First, let's define variables. Let n = number of nickels, and q = number of quarters. If Larry has $4 in nickels and quarters, then our first equation is\r \n" ); document.write( "\n" ); document.write( "0.05n + 0.25q = 4 (since a nickel is 5 cents, and a quarter is 25 cents)\r \n" ); document.write( "\n" ); document.write( "Since there are 36 coins, then n + q = 36\r \n" ); document.write( "\n" ); document.write( "Now, we have to solve the equation simultaneously. We can use the substitution method. We can rewrite the second equation as n = 36 - q, then substitute into the first equation to get:\r \n" ); document.write( "\n" ); document.write( "0.05(36 - q) + 0.25q = 4\r \n" ); document.write( "\n" ); document.write( "Simplify\r \n" ); document.write( "\n" ); document.write( "1.8 - 0.05q + 0.25q = 4\r \n" ); document.write( "\n" ); document.write( "Simplify further:\r \n" ); document.write( "\n" ); document.write( "1.8 + 0.2q = 4\r \n" ); document.write( "\n" ); document.write( "To find q, first subtract 1.8 from both sides of the equation to get:\r \n" ); document.write( "\n" ); document.write( "0.2q = 4 - 1.8 = 2.2\r \n" ); document.write( "\n" ); document.write( "Now, divide both sides by 0.2 to get:\r \n" ); document.write( "\n" ); document.write( "q = 2.2/0.2 = 11\r \n" ); document.write( "\n" ); document.write( "To solve for n, remember n + q = 36\r \n" ); document.write( "\n" ); document.write( "So n + 11 = 36 \n" ); document.write( "subtract 11 from both sides of the equation: \n" ); document.write( "n = 36 - 11 = 25\r \n" ); document.write( "\n" ); document.write( "Now that we have the values of n and q, we can check our answers to make sure we are right.\r \n" ); document.write( "\n" ); document.write( "Equation 1: 0.05n + 0.25q = 4\r \n" ); document.write( "\n" ); document.write( "Let's substitute the values of n and q into the equation to see if it makes the equation true.\r \n" ); document.write( "\n" ); document.write( "0.05(25) + 0.25(11) = 1.25 + 2.75 = 4\r \n" ); document.write( "\n" ); document.write( "Our answer is correct.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |