document.write( "Question 163292: Translate the following into a system of equations, then solve it: A customer walks into an electronics store and buys five MP3 players and eight sets of headphones, paying $840. A second customer buys three MP3 players and four sets of headphones, and pays $480. How much does an MP3 player cost? How much does a set of headphones cost? \n" ); document.write( "

Algebra.Com's Answer #120327 by jojo14344(1513) $\"\"$ $\"About$

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\n" ); document.write( "1st customer:
\n" ); document.write( " $\"5MP%2B8HP=840\"$ ----------------------> eqn 1
\n" ); document.write( "In eqn 1 we get,
\n" ); document.write( " $\"HP%2B%28840-5MP%29%2F8\"$ -------------------> eqn 2
\n" ); document.write( "2nd customer:
\n" ); document.write( " $\"3MP%2B4HP=480\"$ ----------------------> eqn 3
\n" ); document.write( "Subst. eqn 2 in eqn 3:
\n" ); document.write( " $\"3MP%2Bcross%284%291%28%28840-5MP%29%2Fcross%288%292%29=480\"$
\n" ); document.write( " $\"3MP%2B%28%28840-5MP%29%2F2%29=480\"$ , get LCD
\n" ); document.write( " $\"%286MP%2B840-5MP%29%2F2=480\"$ , cross multiply
\n" ); document.write( " $\"6MP-5MP=2%2A480-840=960-840=120\"$
\n" ); document.write( " $\"MP=120%2Fea\"$ , cost of a MP3
\n" ); document.write( "Via eqn 2:
\n" ); document.write( " $\"HP=%28840-5%2A120%29%2F8=%28840-600%29%2F8=240%2F8\"$
\n" ); document.write( " $\"HP=30%2Fea\"$ , cost of Headphone set
\n" ); document.write( "In doubt? GO back eqn 3:
\n" ); document.write( " $\"3%2A120%2B4%2A30=480\"$
\n" ); document.write( " $\"360%2B120=480\"$
\n" ); document.write( " $\"480=480\"$
\n" ); document.write( "Go back eqn 1:
\n" ); document.write( " $\"5%2A120%2B8%2A30=840\"$
\n" ); document.write( " $\"600%2B240=840\"$
\n" ); document.write( " $\"840=840\"$
\n" ); document.write( "Thank you,
\n" ); document.write( "Jojo \n" ); document.write( "

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