Question 696711
Let W = width of rectangle 



"the length of rectangle is three times its width"
then the length = 3W



"if perimeter of rectangle is 96 metres"
{{{ perimeter = 2(length+width) = 96" }}}
{{{ 2(3W+W)=96 }}}
{{{ 2(4W)=96 }}}
{{{ 8W=96 }}}
{{{ W=12 }}}


So the dimensions are:
width=12
length=36



"Find its area"
{{{ Area=width*length = 12*36=432 }}}