Answer:
15x² - 3y + 9
Step-by-step explanation:
(12x² + 6y - 3) + (3x² - 9y + 12)
12x² + 6y - 3 + 3x² - 9y + 12
12x² + 3x² + 6y - 9y + 12 - 3
15x² + 6y - 9y + 12 - 3
15x² - 3y + 12 - 3
The correct answer is 9x² +15y - 15
Let's subtract 12x^2+6y-3 and 3x^2-9y+12:
12x^2 +6y - 3
-
3x^2 -9y + 12
_______________
9x² +15y - 15
