Step-by-step explanation:
step 1. 12x - 15 - 12x = 7x + 20
step 2. 12x - 12x - 15 = 7x + 20 (grouping of terms)
step 3. -15 = 7x + 20 (adding like terms)
step 4. -35 = 7x (subtract 20 from both sides)
step 5. this step is incorrect.
step 6. -5 = x ( divide both sides by 7)
step 7. x = -5 (put the variable first).
