What number would replace x

to show that the Associative Property of Addition is being applied (3+2)+4=x+(2+4)
?

The number that would replace x would be 3.

The Associative Property of Addition states that the grouping of numbers being added does not affect the sum. In the equation given, the numbers inside the parentheses on both sides are being added first before adding with the other numbers. Therefore, x should be equal to the sum of (2+4), which is 6.