Final answer:
The expression for "twice the sum of four and a number" is represented by 2(x + 4) or 2 * (x + 4), signifying that you first sum the number with four and then double the result.
Step-by-step explanation:
The expression that correctly represents "twice the sum of four and a number" is 2(x + 4) or 2 * (x + 4), where x is the variable representing the unknown number. To arrive at this expression, you first find the sum of four and the number (x + 4) and then multiply the result by two to get twice this sum.
In this context, the word 'twice' is similar to triple as in triple the amount of money being three times as much. This operation is an example of simple addition, much like when two numbers are added in any order, such as 2 + 3 or 3 + 2, which illustrates the commutative property of addition.