To solve the equation 2x - 1 - 7 = 9, first

The equation is 2x - 1 - 7 = 9, so the last operation applied to 2x - 1 is subtracting 7. Undo that by adding 7 to both sides, giving 2x - 1 = 16. So the first step is to add 7 to each side.

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