Our current equation is:
3 -6n = 21
To solve for n, we need to get -6n by itself on one side, and then simplify.
Always remember;
What you do to one side of an equation, you must do to the other.
Subtract 3 from both sides.
3 - 3 = 0
21 - 3 = 18.
Your equation now is:
-6n = 18.
N is being multiplied by -6, so we need to perform the opposite order of equations.
Divide both sides by -6.
-6n / -6 = n
18 / -6 = -3
n = 3
I hope this helps!