Hi there!
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Recall the equation:
y = mx + b, where:
m = slope, or gradient of a line
Rewrite this expression into the above format:
3y + 6x = 12
Isolate y by subtracting 6x from both sides of the equal sign:
3y + 6x - 6x = 0x -6x + 12
3y = -6x + 12
Divide all terms by 3:
y = -2x + 4
Thus, the gradient is -2.