Let,
Width(W) of Rectangular =x
Length(L) of Rectangular=3x
So, Rectangular area=3x×x=3x^2
ATQ,
3x^2=768
x^2=256
x=16
Now,Rectangular Perimeter,
=2(L+W)
=2(3x+x)
=8x
=8×16
=128
Rectangular perimeter =Square perimeter
so, Square perimeter,
4x=128
x=32
Area of square=x^2
=32×32
=1024
Need total tiles=1024÷(.8×.8)
=1600 Pieces.