IMAS 2024–2025 — Junior Division — Round 2 Question 1

Question 1

A real-valued function $f$ is defined on all real numbers such that $f(x)\le x$ for all real numbers $x$ and $f(x+y)\le f(x)+f(y)$ for all real numbers $x$ and $y$. What is the numerical value of $f(20)+f(25)$?

$-45$
$-2$
$0$
$2$
$45$