CAT 2022 Number System — Previous Year Question

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