$\underset{Yellow}{F{e}^{3+}\left(aq\right)}+SC{N}^{-}\left(aq\right)\rightleftharpoons \underset{\mathrm{Re}d}{{\left[Fe\left(SCN\right)\right]}^{2+}}\left(aq\right)$
To the equilibrium mixture,  $HgC{l}_2\left(A\right)$ and  $KSCN\left(B\right)$ are added in two separate experiments.  Red colour intensity decreases by the addition of 

$HgC{l}_2$ will remove $SC{N}^{\Theta }$ by forming complex while KSCN will increase $SC{N}^{\Theta }$ when added in solution.  Red colour intensity will decreases by addition of $HgC{l}_2$ as equilibrium will shift in backward direction due to removal of reaction.