Answer:
x= -7
Explanation:
Assuming your asking for the value of x, the answer is -7. Something I never understood about the school's way of teaching is that the equal sign is just a sign. It means that whats on one side of it is always the same as on the other side. 3=3, 9740=9740, it's just a fact. You can do anything to the numbers... As long as you do it to both sides of the = so that they stay the same. therefore if im told 6=6, i can divide both side by 3 and get 2=2. Its still a true statement, 2 does equal 2. If you try to only divide one side of the equal sign, it doesnt work. By only dividing the right side by three, you would get 6=2, and that just isnt true. Doing the same thing to your equation(3x=-21) I can divide BOTH sides by 3.
3x(/3)=-21(/3)
**x times 3, divided by three =x
**-21/3 =-7
x=-7