Answer:
n = -6
x = -7
n = 27
Explanation:
Question 1
-3n - n + 12 = 36
First we get all the variables to one side using subtraction property of equality.
-3n - n + 12 (-12) = 36 (-12)
-4n = 24
divide by the coefficient of n to isolate the variable
-4n/-4 = 24/-4
n = -6
Question 2
-2x - 3x - 15 = 20
-5x - 15 = 20
-5x = 35
x = -7
Question 3
3 + n/9 = 6
Isolate the n variable
n/9 = 6 - 3
multiply by 9
n = 27