Answer: {y,x} = {3,3}
Explanation:
1] y=-4x+15
[2] -4x+7y=9
Equations Simplified or Rearranged :
[1] y + 4x = 15
[2] 7y - 4x = 9
Graphic Representation of the Equations :
4x + y = 15 -4x + 7y = 9
Solve by Substitution :
// Solve equation [1] for the variable y
[1] y = -4x + 15
// Plug this in for variable y in equation [2]
[2] 7•(-4x+15) - 4x = 9
[2] - 32x = -96
// Solve equation [2] for the variable x
[2] 32x = 96
[2] x = 3
// By now we know this much :
y = -4x+15
x = 3
// Use the x value to solve for y
y = -4(3)+15 = 3
Solution :
{y,x} = {3,3}