PROBLEM $04$: Discrete Convolution Operation

The system's equation $y[n]=T\{x[n]\}$ is modeling a fading channel, which is shown in Fig. P$04$ below, as a discrete$-$time filter:

$y[n]={\displaystyle \underset{k=0}{\overset{k=3}{}}}h[k]x[n-k]$

$4$a$.25$ Points.$-$ Compute $y[n]$ if $x[n]=e^{j2n}$;$nin{Z}_3$ and the impulse response function of the filter is given by $h[n]=e^{jn}$;$nin{Z}_4.$