Which of the following represents the first step for solving a system of equations using the substitution method?
y = 4x (I)
y = 7x - 9 (II)
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Option B
y = 4x (I)
y = 7x - 9 (II)
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Substituting y (I) in (II)
4x = 7x - 9
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Option A (it has no sense)
Option C ( (I) + (II) )
Option D ()
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Answer
Opcion B
4x = 7x - 9