Question 19976
This is an expression, meaning it is a sequence of operations and operands. It is algebraic since it contains a number that is unknown and is represented by x.
All the other operands (numbers in the expression) can be used in the operations to find out what they are equal to. For example, 3 + 5 has two operands (3 and 5) and one operation ( + ) and the expression 3 + 5 is equal to 8.
You have
-8x + -(5+3x) - 2
-8x means the negative of 8 times x (whatever number x is, which we don't know!)
-(5+3x) means the neagtive of the quantity 5+3x, and you know what 3x means, right?
and 2
the first number [-8x] is added to the second number [-(5+3x) and then the third number [2] is subtracted from that sum.
This can be simplified by applying the negative of the quantity (5+3x) giving
-5 -+3x. It is usual to write a negative addition as a subtraction, so this becomes -5 - 3x. The whole expression is now
-8x +-5 - 3x - 2
Again, the addition of a negative is usually written as a subtraction, so:
-8x - 5 - 3x - 2
Now terms can be grouped and rearranged.
-8x - 3x - 5 - 2
And arithmetic can be done, giving
-11x -7
That's the simplified expression which will have the same value as the original.
Of course, the value of the expression is unknown until you know what value x represents. Example: if x=3, the expression becomes 
-11(3) -7 == -33 - 7 = -40.
Hope that helps.