Explain why max 2x+y s.t. x+y=m does not have a single solution?

Question

I dont know how to answer the following question.

Explain why max 2x+y s.t. x+y=m does not have a single solution?

Hope someone can explain.

Answer 1

Let $x=t, y=m-t \implies 2x+y=m+t$. This can be arbitrarily large as $t$ varies.