Solve $3x-4y=12$

Step-by-step solution

1. Step 1 · Subtract 3x
   $$-4y=12-3x$$

   Apply the same operation to both sides to preserve equality.

2. Step 2 · Divide by −4
   $$y=\frac{12-3x}{-4}=\frac{3}{4}x-3$$

   Both signs reverse when dividing the numerator terms by a negative number.

3. Step 3 · Check by substitution
   $$3x-4(\frac{3}{4}x-3)=12$$

   The x terms cancel, leaving 12 = 12 for every real x.