Question 191607
Orelan Paint Town sold 45 paintbrushes, one 
kind at $8.50 each and another at $9.75 each. In all, 
$398.75 was taken in for the brushes. How many of 
each kind were sold? 
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Quantity Equation: a + b = 45
Value Equations: 850a+ 975b = 39875 cents
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Multiply thru the 1st by 850 to set it up for elimination:
850a   +  850b  = 850*45
850a   +  975b  = 39875
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Subtract the 1st Eq. from the 2nd so you can solve for "b":
125b = 1625
b = 13 (there are 13 of the $9.75 pens)
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Substitute into a + b = 45 to solve for "a":
a + 13 = 45
a = 32 (there are 32 of the $8.50 pens)
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Cheers,
Stan H.