1) (2ab+3bc)abc=2ab/abc+3bc/abc=2/c+3/a
2) (1/2a1/3b+1/4c)/5/6c=1/6ab/5/6c+1/4c:5/6с=ab/5c+6/20
3) 1/4a(b+2c)/3a=1/12(b+2c)
4) ((7a-4c)2/3b)/2bc=(14ab/3-8cb/3)/2bc=14ab/3*2bc-8cb/3*2bc=7ab/3bc-4/3
5) сокращается 2с и ab в числителе и знаменателе
(3,5a-3,5b)3,5/7c=3,5*3,5(a-b)/7c=12,25(a-b)/7c=1,75(a-b)/c