Final answer:
The sum of the expressions (8 + 2b) + (-4 + 7d) + (9 + 6m), upon combining like terms, is 2b + 7d + 6m + 13.
Step-by-step explanation:
To find the sum of the expressions (8 + 2b) + (-4 + 7d) + (9 + 6m), we simply need to combine like terms. We combine the constants (numbers without variables) and the coefficients (numbers in front of variables) of like terms.
First, let's add the constants: 8 - 4 + 9 = 13.
Next, we can see that there are no like terms for variables b, d, and m to combine with, so we just bring down the terms: 2b, 7d, and 6m.
Therefore, the sum of the expressions is 2b + 7d + 6m + 13, which corresponds to option A: 9b + 7d + 6m + 13 (Note: There appears to be a typo as the correct coefficient for b should be 2, not 9).