3a^2+25a+28/3a+4 =
If that's meant to be a long division or a factorization problem, then vital parentheses are missing:
(3a^2+25a+28)/(3a+4)
=(3a+4)(a+7)/(3a+4)
=(a+7) assuming a≠-4/3
(3a^2+25a+28)/(3a+4)
=(3a+4)(a+7)/(3a+4)
=(a+7) assuming a≠-4/3