To solve 3x + 15 = 0 for x, we can follow the below steps:
1. Set the equation: 3x + 15 = 0.
2. The goal is to isolate x, so first, we will move 15 from the left side to the right side. This operation changes its sign from positive to negative. The equation now looks like this: 3x = -15.
3. Now, to isolate x, we need to remove the coefficient of x, which is 3. We do this by dividing the entire equation by 3: X = -15 / 3.
4. Calculating -15 divided by 3 gives us -5.
So, the solution to our equation 3x + 15 = 0 is x = -5.