Help

By the triangle inequality, the minimum of the remaining side is 80 - 25 = 55.

I'm sorry guest but thet is wrong

Let $s$ and $\ell$ be the shorter and longer of the remaining sides of the triangle. We are told that $25+s+\ell=80$. By the Triangle Inequality, $$s+25>\ell.$$ Adding $\ell$ to both sides of the inequality gives $$\begin{align*} s+25+\ell &> 2\ell \\ 80 &> 2\ell, \end{align*}$$ so the largest value of $\ell$ is $39$. In that case, $s=80-(25+\ell)=80-64=\boxed{16}$.