Solution
= Solution
Choose any vertex $v$ of $K_{2t}$. Its $2t-1$ incident edges have two colours, so at least
$$
\left\lceil\frac{2t-1}{2}\right\rceil=t
$$
have the same colour. Those edges, together with $v$, form a monochromatic $K_{1,t}$.
= Solution
Choose any vertex $v$ of $K_{2t}$. Its $2t-1$ incident edges have two colours, so at least
$$
\left\lceil\frac{2t-1}{2}\right\rceil=t
$$
have the same colour. Those edges, together with $v$, form a monochromatic $K_{1,t}$.