If , then the value of x is:

The correct option is -3.

To find the value of $x$, we simplify the expressions inside the grouping symbols (parentheses, braces, and brackets) step-by-step according to the order of operations.

Step 1: Simplify the innermost parentheses.

In both terms, simplify the product of negative signs:

$-4(-a)=4a$

$-3(-a)=3a$

Step 2: Simplify the expressions inside the curly braces.

Substitute the results from Step 1 into the braces:

First term's brace: $-5\left\{4a\right\}=-20a$

Second term's brace: $-3\left\{3a\right\}=-9a$

Step 3: Simplify the expressions inside the square brackets.

Now substitute the simplified brace values back into the equation:

First term: $x[-20a]=-20ax$

Second term: $6[-9a]=-54a$

Step 4: Rewrite and solve the simplified equation.

Substitute both terms back into the original equation:

$-20ax-54a=6a$

Add $54a$ to both sides:

$-20ax=6a+54a$

$-20ax=60a$

Divide both sides by $-20a$ (assuming $a\ne 0$):

$x=\frac{60a}{-20a}$

$x=-3$

Thus, the value of $x$ is -3.