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What is the first step to solving this system of equations using the substitution method?

x + y = 11
x = -y - 9

Group of answer choices

substitute 11 - x for the x in the bottom equation

substitute -y-9 in for x in the top equation

add the equations together

substitute y=11 in for x in the bottom equation

1 answer

The given system of equations is:

  1. \( x + y = 11 \)
  2. \( x = -y - 9 \)

To use the substitution method, we typically want to solve one of the equations for one variable and then substitute that expression into the other equation.

Looking at the second equation, \( x = -y - 9 \), it is already solved for \( x \). The next step would be to substitute this expression for \( x \) into the first equation.

Therefore, the correct choice is:

substitute -y-9 in for x in the top equation.