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| Question 230434:  The profits of a company that produces auto parts can be represented by a linear function. If the company sells 25 parts its profits are $80 and if the company sells 40 parts its profits are $125. Find the number of parts sold if the profits were $305. If the profits were $905.
 Answer by texttutoring(324)
      (Show Source): 
You can put this solution on YOUR website! Let x=the number of parts sold Let y =the profit
 Find the slope of the linear equation by using the slope formula:
 m=(y2-y1)/(x2-x1)
 In this case, y2=$125, y1=$80. x2=40, x1=25.
 m=($125-$80)/40-25= $45/15
 m=$3/part
 We need to find the y-intercept (or b).
 y=mx+b
 I can choose either point (40,125) or (25,80).
 y=mx+b
 125=3*40+b
 125=120+b
 125-120=b
 5=b
 The line's equation is:
 y=3x+5
 If profits are $305:
 305=3x+5
 300=3x
 x=100
 If profits are $305, 100 parts were sold.
 If profits are $905:
 905=3x+5
 900=3x
 x=300
 If profits were $905, 300 parts were sold.
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