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A cleaning company charges x dollars per hour to clean floors and y dollars per hour to clean the rest of the house
-when the company spends 2 hours to clean floors and 3 hours to clean the rest of a house,the total is $84.
-when the company spends 1 hour to clean floors and 4 hours to clean the rest of a house,the total is $87

Which ordered pair represents the hourly charges to clean floor and to clean the rest of the house?

A.(12,20)
B.(15,18)
C.(20,12)
D.(18,15)

Respuesta :

Answer:

(15,18)

Step-by-step explanation:

write two equations with the information provided.

2x + 3y = 84

x + 4y = 87

use the property of substitution to answer.

x + 4y = 87,   x = 87 - 4y

2(87 - 4y) + 3y = 84

174 - 8y + 3y = 84

174 - 84 = 8y - 3y

90 = 5y

90/5 = y

y = 18

Add the value of Y to an original equation. Solve for X

2x + 3(18) = 84

2x + 54 = 84

2x = 84 - 54

2x = 30

x = 30/2

x = 15

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