Упростите выражение (a/b+9b/a-6) * 1/a-3b

(a²+9ab-6ab)/ab)*b/ab-3ab/ab= =(a²+3ab)/ab)*b/ab-3ab/ab= =(a²b+3ab²-3ab)/ab= =(ab(a+3b-3)/ab= =a+3b-3