invert an multiply
(a/b)/(c/d)=(a/b)(d/c)=(ad)/(bc)
1..
(4x/45)/(12x/25)=(4x/45)(25/12x)=(100x)/(540x)=5/27
2.
(x/9)/(3x/2)=(x/9)(2/3x)=(2x)/(27x)=2/27
3.
(7x/9)/(49/3x)=(7x/9)(3x/49)=(21x^2)/(441)=(x^2)/21
4.
(2x^2y/3yz)/(6/xz)=(2x^2y/3yz)(xz/6)=(x^3)/(9)
5. (4y-3x)/(3xy+y^2)
6. (-9x+6)/(8x+6)
7. (yx^2+y^2)/(x^2+xy^2)
8. x^-1=1/x
(x^2)/(4x+1)
