Answer:
x = 9
Step-by-step explanation:
Given equation:

Apply distributive property rule: x(y + z) = xy + xz



Combine like terms on the left hand side to simplify the expression:



Add 21 on both sides to remove all the mathematical operations (addition, subtraction, multiplication, division) being performed on the L.H.S


Cancel the "-" by dividing "-1" both sides:

Divide 3 on both sides to isolate the coefficient from x.


<h3>Check:</h3>
Now, let's check our answer. This can be done by substituting the obtained value of "x", into the given equation and simplifying it.
<u>Correct/Incorrect:</u>
If L.H.S = R.H.S, then the value of "x" is correct.
If L.H.S ≠ R.H.S, then we might have to recheck our work we did above.

Plugging x = 9 into the equation:
![\implies -4[2(9) + 5] + 5(9) - 1 = -48](https://tex.z-dn.net/?f=%5Cimplies%20-4%5B2%289%29%20%2B%205%5D%20%2B%205%289%29%20-%201%20%3D%20-48)
Simplifying the expression using PEMDAS:
![\implies -4[18 + 5] + 5(9) - 1 = -48](https://tex.z-dn.net/?f=%5Cimplies%20-4%5B18%20%2B%205%5D%20%2B%205%289%29%20-%201%20%3D%20-48)
Simplifying the expression inside the parentheses (18 + 5) and evaluating the product of 5 and 9:
![\implies -4[23] + 45 - 1 = -48](https://tex.z-dn.net/?f=%5Cimplies%20-4%5B23%5D%20%2B%2045%20-%201%20%3D%20-48)
Opening the parentheses "-4[23]" and multiplying -4 and 23

Subtracting 45 both sides of the equation:


Simplifying the L.H.S:

Therefore, our answer is correct.