document.write( "Question 979964: Phineas has $1.15 worth of coin in his pocket. He has three more dimes than quarters and two more dimes than nickels. How much does he have in each coin? \n" ); document.write( "
Algebra.Com's Answer #601191 by RicaMath(8)![]() ![]() ![]() You can put this solution on YOUR website! This problem can be solved by writing a few algebraic equations.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's define the following variables: \n" ); document.write( "d = number of dimes \n" ); document.write( "n = number of nickels \n" ); document.write( "q = number of quarters\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The problem states that the sum of all of these coins is $1.15. Translating this into an equation, you get 0.1d + 0.05n + 0.25q = 1.15 (multiply each variable by the monetary value of each coin)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's convert the rest of the statements into equations.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "He has three more dimes than quarters \n" ); document.write( "d = q + 3 (the number of dimes equals 3 more than the number of quarters)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "...and two more dimes than nickels. \n" ); document.write( "d = n + 2 (the number of dimes equals 2 more than the number of nickels)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Next, we solve for each variable by doing a series of substitutions. We can equate the two equations above together to temporarily remove d, and then solve for one of the variables. For this, I will solve for n.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "q + 3 = n + 2 \n" ); document.write( "n = q + 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now, I will plug in this value of n into the first equation and solve for d.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0.1d + 0.05n + 0.25q = 1.15 \n" ); document.write( "0.1d + 0.05(q + 1) + 0.25q = 1.15 \n" ); document.write( "0.1d + 0.05q + 0.05 + 0.25q = 1.15 \n" ); document.write( "0.1d + 0.3q = 1.1 \n" ); document.write( "0.1d = 1.1 - 0.3q \n" ); document.write( "d = 11 - 3q\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "I can then plug this into the equation d = q + 3 and solve for q.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "11 - 3q = q + 3 \n" ); document.write( "-4q = -8 \n" ); document.write( "q = 2 \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now that I know q = 2, I can plug this into d = q + 3 to solve for d.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "d = 2 + 3 \n" ); document.write( "d = 5\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Last step is to take d = 5 and solve for n. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "d = n + 2 \n" ); document.write( "5 = n + 2 \n" ); document.write( "n = 3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "---\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "To check the answer, we can plug these values into the original equation:\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "0.1d + 0.05n + 0.25q = 1.15 \n" ); document.write( "0.1(5) + 0.05(3) + 0.25(2) = 1.15 \n" ); document.write( "0.5 + 0.15 + 0.5 = 1.15 \n" ); document.write( "1.15 = 1.15\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The equation checks out! \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Final answer: Phineas has 2 quarters, 5 dimes, and 3 nickels. \n" ); document.write( " |