Final answer:
To simplify the expression x^2 + 12x + 35 / 3x + 15, factor the numerator and denominator separately, cancel out the common factor, and simplify the remaining expression.
Step-by-step explanation:
To simplify the expression x^2 + 12x + 35 / 3x + 15, we can factor the numerator and denominator separately.
The numerator can be factored as (x + 5)(x + 7), and the denominator can be factored as 3(x + 5). Canceling out the common factor (x + 5), we are left with (x + 7) / 3.
Therefore, the completely simplified expression is x + 7/3 (option C).