Question 363007
materials for a mountain bike is $70,
cost of materials for a trail bike is $50. 
cost of labor to manufacture a mountain bike is $80,
cost of labor to manufacture a trail bike is $40. 
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budgeted $2500 for materials 
$2600 for labor, 
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let x be mountain bikes
y be trail bikes
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70x+50y=2500.......................1
80x+40y=2600.......................2
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multiply equation 1 by -8 & equation 2 by 7
-560x-400y=-20000
560x+280y=18200
add the two
-120y= -1800
/-120
y=1800/-120 
y =15 trail bikes
plug the value of y 
70x+50*15=2500
70x=2500-750
70x=1750
x= 25 mountain bikes
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m.ananth@hotmail.ca