Problem

Source: Bulgaria JBMO TST 2017, Day 2, Problem 3

Tags: inequalities



Prove for all positive real numbers $m,n,p,q$ that $$\frac{m}{t+n+p+q} + \frac{n}{t+p+q+m} + \frac{p}{t+q+m+n} + \frac{q}{t+m+n+p} \geq \frac{4}{5},$$where $t=\frac{m+n+p+q}{2}.$