x-7y/xy - x-4y/xy= (x-7y – (x-4y)) /xy=(x-7y – x+4y)/xy=-3y/ху=-3/х;
10a+6b/11a^3 - 6b-a/11a^3= (10a+6b- (6b-a))/11a^3=(10a+6b- 6b+a))/11a^3=11а/11a^3=1/а^2 ;
x^2-xy/x^2y + 2xy-3x^2/x^2y= (x^2-xy+2xy-3x^2) /x^2y=( xy- 2x^2) /x^2y=х(у-2х)/ x^2y= (у-2х)/ xy;