Hello!
Step 1. Simplify the equation... 3x+4-12x
Step 2. Add 12x to both sides... 3x+4+12x=−12x+12x
15x+4=0
Step 3. Subtract 4 from both sides... 15x+4−4=0−4
15x=-4
Step 4. Divide both sides by 15...15x/15=−4/15
X=-4/15
Final Answer: x=-4/15
Hope I could help! :)