You calculate an answer by multiplying each side by each other. hope this helps.
Answer:

Step-by-step explanation:
subtract 3 from both sides


divide each term by 6


simplify

To solve this problem just do the following,
x+9=-12
-9 -9
x=-21
Check
-21+9=-12 = True
Hope this helps!=)
Answer:
the answer is -3
Step-by-step explanation:
1. add the -4 to 10 (-10 + 4)
2. -6= 2a
3. divide both sides by 2
4. -3= a
hope this helps