Answer
$Please\space see\space the\space work\space step\space by\space step$
Work Step by Step
Let's take the following parameters for easy calculation.
$a\space = Number\space of\space news\space papers\space production\space by\space \space one\space tree $
$b\space = Number\space of\space news\space papers\space production\space in\space one\space day $
So we can write,
No. of one-day newspapers production by trees $=b/2$
number of trees that go into one day's printing $=(\frac{b}{2}\times\frac{1}{a})=\frac{b}{2a}$
