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A shoe salesperson sold 20 pairs of shoes for $640. A brown pair of shoes sells for $30 and a black pair for $35. How many brown pairs were sold? A. 12 B. 14 C. 15 D. 8​

Respuesta :

MrRoyal

Answer:

12 pairs

Step-by-step explanation:

Represent Brown with B and Black with A

So:

[tex]A + B = 20[/tex] --- Pairs sold

[tex]30B + 35A = 640[/tex] --- Amount

Required

Solve for B (the brown pairs)

Make A the subject in the first equation

[tex]A = 20 - B[/tex]

Substitute 20 - B for A in the second

[tex]30B + 35(20-B) = 640[/tex]

Open bracket

[tex]30B + 700 - 35B = 640[/tex]

Collect Like Terms

[tex]30B - 35B = 640 -700[/tex]

[tex]-5B = -60[/tex]

Divide both sides by -5

[tex]B = \frac{-60}{-5}[/tex]

[tex]B =12[/tex]

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