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The sum of two numbers is 84. If four times the smaller number is subtracted from the larger number the result is 14. Find the two numbers

Respuesta :

Answer:

y=14

Step-by-step explanation:

x + y = 84

-1(x - 4y = 14)

-x + 4y = -14

x + y = 84

-x + 4y = -14

5y = 70

divide by 5

y = 14

Answer: 70 and 14

Step-by-step explanation:

Let the bigger number be x and the smaller number be y , then from the first statement

[tex]x + y = 84[/tex]

From the second statement :

four times the smaller number means [tex]4[/tex] x [tex]y[/tex] , which will be [tex]4y[/tex] , so

four times the smaller number is subtracted from the larger number the result is 14 means :

[tex]x - 4y = 14[/tex]

combining the two equations we have :

[tex]x + y = 84[/tex] ........................... equation 1

[tex]x - 4y = 14[/tex] .......................... equation 2

solving the system of linear equation by substitution method , from equation 1 , make x the subject of the formula , that is :

[tex]x = 84 - y[/tex] .......................... equation 3

substitute [tex]x = 84 - y[/tex] into equation 2 , that is

[tex]84 - y - 4y = 14[/tex]

[tex]84 - 5y = 14[/tex]

[tex]84 - 14 = 5y[/tex]

[tex]70 = 5y[/tex]

therefore :

[tex]y = 14[/tex]

substitute [tex]y = 14[/tex] into equation 3 to find the value of x

[tex]x = 84 - y[/tex]

[tex]x = 84 - 14[/tex]

[tex]x = 70[/tex]

check :

[tex]x + y = 84[/tex]

[tex]70 + 14 = 84[/tex]

[tex]x - 4y = 14[/tex]

[tex]70 - 4( 14 )[/tex]

[tex]70 - 56 = 14[/tex]

Therefore : the bigger number is 70 and the smaller number is 14