Let $A$ be the largest positive integer that divides all the numbers of the form $3^{k}+4^{k}+5^{k}$, and $B$ be the largest positive integer that divides all the numbers of the form $4^{k}+3\left(4^{k}\right)+4^{k+2}$, where $k$ is any positive integer. Then $(A+B)$ equals