the dimension of a rectangular box are 2x^2-7xy+3y/x^2-4y^2, 2x+4b/6x-3y and x^2-xy-2y^2/x^2-4xy-4y^2, find its volume using the volume, v=

You have not used any brackets which means that the lengths are likely to be interpreted wrongly.

these are the lengths given, are they the lengths that were intended? (Probably not)

Please add brackets and were can continue with the question.  Thanks.

Remember: Too many brackets is usually better than not enough!

$$\\2x^2-7xy+\frac{3y}{x^2}-4y^2,\qquad 2x+\frac{4b}{6}x-3y, \qquad x^2-xy-\frac{2y^2}{x^2}-4xy-4y^2$$