Answer
$42$
Work Step by Step
We know that $\log_a {x}+\log_a {y}=\log_a {(x\cdot y)}$.
Hence,
$5^{\log_5{6}+\log_5 {7}}=5^{\log_5 {(6\cdot 7)}}=5^{\log_5{42}}$.
We also know that $a^{\log_a {x}}=x$.
Thus,
$5^{\log_5 {42}}=42$