document.write( "Question 1188695: A man bought a number of 12p stamps and also sufficient 16p stamps to make his total expenditure £4.80. If, instead of the 12p stamps, he had bought three times as many 8p stamps he would have needed 9 fewer 16 stamps than before for his expenditure to be £4.80. Find how many 12p Stamps he bought. \n" ); document.write( "

Algebra.Com's Answer #819834 by ikleyn(52788) $\"\"$ $\"About$

You can put this solution on YOUR website!
.
\n" ); document.write( "A man bought a number of 12p stamps and also sufficient 16p stamps to make his total expenditure £4.80.
\n" ); document.write( "If, instead of the 12p stamps, he had bought three times as many 8p stamps he would have needed 9 fewer
\n" ); document.write( "16 stamps than before for his expenditure to be £4.80. Find how many 12p Stamps he bought.
\n" ); document.write( "~~~~~~~~~~~~~~~~\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "

\r\n" );
document.write( "x = the number of the 12p stamps;\r\n" );
document.write( "\r\n" );
document.write( "y = the number of the 16p stamps.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Write two equations as you read the problem\r\n" );
document.write( "\r\n" );
document.write( "    12x    +  16y    = 480      (1)\r\n" );
document.write( "\r\n" );
document.write( "    8*(3x) + 16(y-9) = 480      (2)\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Simplify to the standard form system of linear equations.\r\n" );
document.write( "\r\n" );
document.write( "    12x + 16y = 480             (3)\r\n" );
document.write( "\r\n" );
document.write( "    24x + 16y = 624             (4)\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Subtract equation (3) from equation (4) to eliminate the terms with \"y\"\r\n" );
document.write( "\r\n" );
document.write( "     12x      = 624 - 480 = 144\r\n" );
document.write( "\r\n" );
document.write( "       x                  = 144/12 = 12.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "ANSWER.  The man bought twelve 12p stamps.\r\n" );
document.write( "

\r
\n" ); document.write( "\n" ); document.write( "Solved.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );