Will give first answer brainliest use the substitution method to solve the system of equations. 3x + 7y = 1 y = x – 7 a. (3, –4) b. (4, –3) c. (2, –5) d. (5, –2)

{x,y} = {12,5}

Step-by-step explanation:

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3x-7y=1;-x+y=-7

Solution :

{x,y} = {12,5}

System of Linear Equations entered :

  [1]    3x - 7y = 1

  [2]    -x + y = -7

Graphic Representation of the Equations :

   -7y + 3x = 1        y - x = -7  

Solve by Substitution :

// Solve equation [2] for the variable  y

 [2]    y = x - 7

// Plug this in for variable  y  in equation [1]

  [1]    3x - 7•(x -7) = 1

  [1]    -4x = -48

// Solve equation [1] for the variable  x

  [1]    4x = 48

  [1]    x = 12

// By now we know this much :

   x = 12

   y = x-7

// Use the  x  value to solve for  y

   y = (12)-7 = 5

Solution :

{x,y} = {12,5}

5   1/4   miles per hour

step-by-step explanation:

15   3/4 / 3 = 5   1/4