document.write( "Question 513652: the science company finds out that when it sells systems for $1200 each, they sell 70 systems per month. when the price drops to $1100, they sell 75 systems per month.\r
\n" ); document.write( "\n" ); document.write( "let x be the number of systems sold and y be the selling price. write an equation for a line that relates the sales to the price. \n" ); document.write( "
Algebra.Com's Answer #343071 by Sarpi(32)\"\" \"About 
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Let x be the number of systems sold = Quantity
\n" ); document.write( "Let y be the selling price = Price\r
\n" ); document.write( "\n" ); document.write( " x y
\n" ); document.write( "70 1200
\n" ); document.write( "75 1100\r
\n" ); document.write( "\n" ); document.write( "Step 1:
\n" ); document.write( "Finding the slope, m = \"%28Y1-Y%29%2F%28X1-X%29\"
\n" ); document.write( " = \"%281100-1200%29%2F%2875-70%29\"
\n" ); document.write( " = -20\r
\n" ); document.write( "\n" ); document.write( "Step 2:
\n" ); document.write( "Find the equation of the line; y= mx+c
\n" ); document.write( "if x=70 and y=1200 then c?\r
\n" ); document.write( "\n" ); document.write( "1200 = -20(70)+c
\n" ); document.write( "1200 = -1400 + c
\n" ); document.write( "1200+1400 = c
\n" ); document.write( " c = 2600
\n" ); document.write( "Finally;
\n" ); document.write( "The equation is y = -20x+2600
\n" ); document.write( " \n" ); document.write( "
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