Solution (source code)

= Solution

Given $\epsilon>0$, choose $\delta=\epsilon/K>0$. If $d_X(x,x')<\delta$, the <Lipschitz condition> yields
$$
d_Y(f(x),f(x'))\leq Kd_X(x,x')<K\delta=\epsilon.
$$
This single $\delta$ works for every pair, proving the map is <uniformly continuous>:
$$
\boxed{\delta(\epsilon)=\epsilon/K.}
$$