What is the solution for x in the equation 3(x + 4) = 21?

To find the solution for x in the equation 3(x + 4) = 21, we start by simplifying the equation step by step.

First, distribute the 3 across the terms inside the parentheses:

3 * x + 3 * 4 = 21

This gives us:

3x + 12 = 21

Next, isolate the term with x by subtracting 12 from both sides of the equation:

3x + 12 - 12 = 21 - 12

This simplifies to:

3x = 9

Now, to solve for x, divide both sides by 3:

3x / 3 = 9 / 3

This results in:

x = 3

This makes x = 3 the correct solution. It demonstrates the process of solving a linear equation by applying arithmetic operations systematically to isolate the variable. Thus, understanding how to manipulate the equation step by step leads directly to identifying the correct value of x.