The 2 lengths + 2 widths of the rectangle will equal 160 meters
So, for example, length = 50 m and width = 30m would fit the bill
2*50 + 2*30 = 160 m
3 * ln 4x = 13
<span><=> </span>
<span>ln 4x = 13/3 </span>
<span><=> </span>
<span>4x = e^(13/3) </span>
<span><=> </span>
<span>x = e^(13/3) / 4 </span>
<span><=> </span>
<span>x ~ 19.05 </span>
