Answer
$y=e^{x/2}$ ; $z=e^x$ and $z=y^2$
Work Step by Step
Here, we have $x=2t; y=e^t; z=e^{2t}$
Now,
$y=e^t=e^{2t/2}=e^{x/2}$
From $z=e^{2t}$, we have $z=e^x$
Also, $z=e^{2t} \implies z=(e^t)^2=y^2$
Hence, we have
$y=e^{x/2}$ ; $z=e^x$ and $z=y^2$