Respuesta :

Answer:

x=-20

Step-by-step explanation:

  • We know that y=-2x
  • We substitute our Y into the main equation: -4x+8(-2x)=40
  • Calculate: -4x-16x=40

                          -20x=40

  • Switch the values to make x positive: -40 = 20x
  • divide both sides by 20 to get x: -40÷20 = 20x÷20
  • You should be left with: x=-20

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