This is the concept of algebra, let the width be x
height=x-4
length=2x+10
the volume of the box is:
volume=length*width*height
=x(x-4)(2x+10)
expanding the above we get:
(x^2-4x)(2x+10)
=x^2(2x+10)-4x(2x+10)
=2x^3+2x^2-40x=264
solving the above we get real solution will be
x=6
thus we conclude that the width is x=6 inches
length=2*6+10=22 inches
height=x-4=6-4=2 inches
thus the dimension will be:
width=6 inches, length=22 inches, height=2 inches