document.write( "Question 1062666: When bottles of water cost $.80 per bottle at softball games, 200 bottles were sold. When the price was raised to $1.00 per bottle, only 150 bottles were sold. Determine the number of bottles of water sold if the price was $.90 per bottle.\r
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Algebra.Com's Answer #677625 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
There is an inverse linear relation ( I assume ) between
\n" ); document.write( "price of bottles and number of bottles sold
\n" ); document.write( "You are given 2 points on the line:
\n" ); document.write( "( 200, .8 ) and
\n" ); document.write( "( 150, 1 )
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\n" ); document.write( "Let \"+n+\" = number of bottles sold
\n" ); document.write( "Let \"+p+\" = price/bottle for \"+n+\" bottles sold
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\n" ); document.write( "Use the point-slope formula
\n" ); document.write( "\"+%28+p+-+.8+%29+%2F+%28+n+-+200+%29+=+%28+1+-+.8+%29+%2F+%28+150+-+200+%29+\"
\n" ); document.write( "\"+%28+p+-+.8+%29+%2F+%28+n+-+200+%29+=+.2+%2F+%28-50+%29+\"
\n" ); document.write( "Multiply both sides by \"+%28+n+-+200+%29%2A%28+-50+%29+\"
\n" ); document.write( "\"+%28+-50+%29%2A%28+p+-+.8+%29+=+.2%2A%28+n+-+200+%29+\"
\n" ); document.write( "\"+-50p+%2B+40+=+.2n+-+40+\"
\n" ); document.write( "\"+-50p+=+.2n+-+80+\"
\n" ); document.write( "Multiply both sides by \"+-1+\"
\n" ); document.write( "\"+50p+=+-.2n+%2B+80+\"
\n" ); document.write( "\"+p+=+-+.004n+%2B+1.6+\"
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\n" ); document.write( "If \"+p+=+.9+\"
\n" ); document.write( "\"+.9+=+-.004n+%2B+1.6+\"
\n" ); document.write( "\"+.004n+=+.7+\"
\n" ); document.write( "\"+n+=+175+\"
\n" ); document.write( "175 bottles will be sold at $.90/bottle
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\n" ); document.write( "check:
\n" ); document.write( "Does the equation go through ( 200, .8 ) ?
\n" ); document.write( "\"+p+=+-+.004n+%2B+1.6+\"
\n" ); document.write( "\"+.8+=+-+.004%2A200+%2B+1.6+\"
\n" ); document.write( "\"+.8+=+-.8+%2B+1.6+\"
\n" ); document.write( "\"+.8+=+.8+\"
\n" ); document.write( "OK
\n" ); document.write( "Does the equation go through ( 150,1 ) ?
\n" ); document.write( "\"+p+=+-+.004n+%2B+1.6+\"
\n" ); document.write( "\"+1+=+-+.004%2A150+%2B+1.6+\"
\n" ); document.write( "\"+1+=+-+.6+%2B+1.6+\"
\n" ); document.write( "\"+1+=+1+\"
\n" ); document.write( "OK\r
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