Given that the contaminated region is a square, the area is given by the formula:
Area=length*width
since in a square length=width
the
area=length×length
or
area=width×width
thus given that area=4m^4/144n^4 sq. units let the width be w units
thus
area=w×w=4m^4/144n^4
w²=4m^4/144n^4
solving for w we get:
w=√(4m^4/144n^4 )
w=2m²/12n²
Hence the width,w=2m²/12n²