1/х + 3/(2 2/5 х)=3/4 х≠0
1/х+(3*5)/12х =3/4
12+15=3*3х
9х=27
х=27:9
х=3
1/3 +3/(12/5 * 3)=3/4
1/3+5/12=4/12+5/12=9/12=3/4 - верно
1/х - 2/( 4 2/3 х) =2/7 х≠0
1/х - (2*3)/14х =2/7
14 - 6=2*2х
4х=8
х=2
1/2 - 2/(14/3 * 2)=1/2 - 6/28=14/28-6/28=8/28=2/7 - верно
6/(3 1/3 х)+1/х=2/5
(6*3)/10х +1/х=2/5
18+10=2*2х
4х=28
х=7
6/(3 1/3 * 7)+1/7=18/70+1/7=18/70+10/70=28/70=4/10=2/5 - верно