Question 248843
Salary = Base + Commission
.
Company A:
Base = $200 
Commission = 10% of sales = .1*S
A = .1S + 200
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Company B:
Base = 400
Commission = .05*S
B = .05S + 400
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We're looking for the point where they're equal.
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200 + .1S = 400 + .05S
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multiply by 100 to get rid of decimals
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20000 + 10S = 40000 + 5S
Subtract 20000 from both sides
10S = 20000 + 5S
Subtract 5S from both sides
5S = 20000
Divide both sides by 5
S = 4000
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So, at $4000 sales, the two jobs pay the same.
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You have to always check your work.  This can be done by plugging the values into the basic equations and determining if they check.  Or we can graph the two lines and see where they cross.
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Company A:
200 + .1(4000) = 200 + 400 = 600
Company B:
400 + .05(4000) = 400 + 200 = 600
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Graphs
{{{
graph(500,500,-500,5000,-500,1000,.1*x+200,.05*x+400)
}}}