84. 1) 14/21 = 2/3
2) 8/14 = 4/7
3) 15/10 = 1,5
4) 27/18 = 3/2 = 1,5
5) 18/24 = 3/4 = 0,75
6) 36/54 = 2/3
7) 20/35 = 4/7
8) 6/8 = 3/4 = 0,75
85. 4) 6/х = 3/7
х = 35/3
5) 5/9 = 15/х
х = 27
6) 12/7 = 60/х
х = 35
86. 1) 8/14 = х/35
х = 20
2) 7/28 = х/12
х = 3
3) 4/х = 6/18
х = 12