Senior Mathematical Challenge 2006 Q20

A positive number $a=[a]+\left\{a\right\}$ where $[a]$ is the integer part of $a$ and $\left\{a\right\}$ is the fractional part of $a$.

Given that $x+\left[y\right]+\left\{z\right\}=4.2$, $y+\left[z\right]+\left\{x\right\}=3.6$, $z+\left[x\right]+\left\{y\right\}=2.0$ and $x,y,z>0$, what is the value of $\left\{y\right\}$ ?