Question

what is the justification for the step taken from line 2 to line 3? 3x + 9 - 7x = x + 10 + x -4x + 9 = 2x + 10 -6x + 9 = 10 -6x = 1 x = -\frac{1}{6} the subtraction property of equality the multiplication property of equality combining like terms on one side of the equation the distributive property

Explanation:

From line 2 ($-4x + 9=2x + 10$) to line 3 ($-6x + 9 = 10$), we subtract $2x$ from both sides of the equation. This follows the subtraction property of equality which states that if we subtract the same number from both sides of an equation, the equality still holds.

Answer:

the subtraction property of equality