Question 128099
tyrel bought 4 pensand 5 pencils, which cost him $6.71. dalia bought 5 pens and 3 pencils, which cost her $7.12. Let A equal the price of a pen. let B equal the price of a pencil. 
a. write an equation that relates the number of pens and pencils tyrel bought to the amount he paid for them.
EQUATION:
4A + 5B = 6.71
5A + 3B = 7.12
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Multiply the 1st equation by 5 and the 2nd equation by 4 to get:
20A + 25B = 5*6.71
20A + 12B = 4*7.12
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Subtract the 2nd equation from the 1st to get:
13B = 5.07
B = 39 cents (price of a pencil)
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Substitute to solve for A:
4A + 5(0.39) = 6.71
4A = 4.76
A = $1.19 (price of a pen) 
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Cheers,
Stan H.