Final answer:
The missing number in the equation _ + 6 = 4 + 9 is 7. By subtracting 6 from both sides, we find that 7 + 6 equals the sum of 4 + 9, which is 13.
Step-by-step explanation:
To solve the equation _ + 6 = 4 + 9, we first need to understand that the commutative property of addition states that A + B = B + A. This property tells us that the order in which numbers are added does not change their sum. In our case, we need to find the missing number that will give us the same result on both sides of the equation when added to 6.
First, we calculate the sum on the right side of the equation:
Next, to find the missing number (let's call it 'x'), we set up the equation:
To solve for 'x', we subtract 6 from both sides of the equation:
So, the missing number is 7, as it satisfies the equation 7 + 6 = 4 + 9.