Answer:
w = -8
Step-by-step explanation:
12-6(w-3)=3(-5-3w)+21 (expand parentheses)
12-6(w)-(-6)(3)= (3)(-5) - (3)(3w) +21
12 - 6w + 18 = -15 -9w + 21
-6w + 30 = 6 - 9w (add 9w to both sides)
-6w + 30 + 9w = 6
3w + 30 = 6 (subtract 20 from both sides)
3w = 6 - 30
3w = -24 (divide both sides by 3)
w = -24 ÷ 3
w = -8