document.write( "Question 826447: An office supply store in new york sells 7 tablets and 4 pens for $6.40. Also , two tablets and 19 pens cost $5.40. Find the price of each \n" ); document.write( "

Algebra.Com's Answer #498074 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = the cost for 1 tablet in cents
\n" ); document.write( "Let $\"+b+\"$ = the cost of 1 pen in cents
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\n" ); document.write( "(1) $\"+7a+%2B+4b+=+640+\"$
\n" ); document.write( "(2) $\"+2a+%2B+19b+=+540+\"$ ( in cents )
\n" ); document.write( "-------------------
\n" ); document.write( "Multiply both sides of (1) by $\"2\"$
\n" ); document.write( "Multiply both sides of (2) by $\"+7+\"$
\n" ); document.write( "Subtract (1) from (2)
\n" ); document.write( "------------------
\n" ); document.write( "(2) $\"+14a+%2B+133b+=+3780+\"$
\n" ); document.write( "(1) $\"+-14a+-+8b+=+-1280+\"$
\n" ); document.write( " $\"+125b+=+2500+\"$
\n" ); document.write( " $\"+b+=+20+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+7a+%2B+4%2A20+=+640+\"$
\n" ); document.write( "(1) $\"+7a+=+640+-+80+\"$
\n" ); document.write( "(1) $\"+7a+=+560+\"$
\n" ); document.write( "(1) $\"+a+=+80+\"$
\n" ); document.write( "---------------
\n" ); document.write( "The price of a tablet is 80 cents
\n" ); document.write( "The price of a pen is 20 cents
\n" ); document.write( "--------------------------
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+2%2A80+%2B+19%2A20+=+540+\"$
\n" ); document.write( "(2) $\"+160+%2B+380+=+540+\"$
\n" ); document.write( "(2) $\"+540+=+540+\"$
\n" ); document.write( "OK\r
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