[tex]1day=\frac{1}{7}week\\\\4\ bags\ for\ 1\ week\\
x\ bags\ for\ \frac{1}{7}\ week\\\\
cross\ multipliction:\\
4*\frac{1}{7}=x\\
x=\frac{4}{7}\\\\
In\ one\ bag\ there\ is\ \frac{3}{5}kg\ of\ corn\\
In\ \frac{4}{7}\ of\ bag\ there\ is:\\
\frac{4}{7}*\frac{3}{5}kg=\frac{12}{35}kg\\\\
He \ need\ \frac{12}{35}kg\ of\ corn\ each\ day.
[/tex]