1) х+3/65 = 4/13
Х=4/13-3/65
Х=20/65-3/65
Х=17/65
2) 7/х+4 = 21/60
21(х+4)=60*7
21(х+4)=420
Х+4=420:21
Х+4=20
Х=20-4
Х=16
3) 5х-8/5 = 18/45
45(5х-8)=18*5
45(5х-8)=90
5х-8=90:45
5х-8=2
5х=2+8
5х=10
Х=10:5
Х=2
