(5m+2 5m-2) 20m
____ --- ____ : ____ 2
(5m-2 5m+2) 12-75m

((5m+2)/(5m-2)-(5m-2)/(5m+2)):(20m/(12-75m²))
1) (5m+2)/(5m-2)-(5m-2)/(5m+2)=((5m+2)²-(5m-2)²)/((5m+2)(5m-2))=
=(25m²+20m+4-25m²+20m-4)/(25m²-4)=40m/(25m²-4).
2)20m/(12-75m²)=20m/(3*(4-25m²))=-20m/(3*(25m²-4)).
3) (40m/(25m²-4)):(-20m/(3*(25m²-4))=40m*(3*(25m²-4))/(-20m*(25m²-4))=-6.