To solve this equation, we need to simplify the expression on the left side and then solve for x.

First, let's simplify the expression inside the brackets:

(6x - 39) ÷ 7

To divide by 7, we can multiply by its reciprocal, which is 1/7:

(6x - 39) × (1/7)

Now, let's distribute the 1/7 to each term inside the brackets:

(6x/7) - (39/7)

Simplifying further, we have:

(6/7)x - (39/7)

Now, let's multiply this expression by 4:

4[(6/7)x - (39/7)]

Distributing the 4 to each term inside the brackets:

(4 * 6/7)x - (4 * 39/7)

Simplifying further:

(24/7)x - (156/7)

Now, we have the equation:

(24/7)x - (156/7) = 12

To solve for x, we need to isolate the variable. Let's start by adding (156/7) to both sides of the equation:

(24/7)x - (156/7) + (156/7) = 12 + (156/7)

Simplifying:

(24/7)x = 12 + (156/7)

Next, let's combine the fractions on the right side:

(24/7)x = (84/7) + (156/7)

(24/7)x = (240/7)

To get rid of the fraction on the left side, we can multiply both sides of the equation by the reciprocal of (24/7), which is 7/24:

(7/24)(24/7)x = (7/24)(240/7)

Simplifying:

x = 240/24

Reducing the fraction:

x = 10

Therefore, the solution to the equation is x = 10.