1. 27/36=7/12, 50/75=10/15=2/3, 18/24=3/4, 28*5/15*14=2/3
2. 4/9=16/36, 6/15=2/3
3. 7/18 и 5/12, 14/36 и 15/36, 5/14 и 8/21, 15/42 и 16/42
4. 30/36 и 14/35, 1050/1260 и 504/1260, 21/70 и 28/105, 126/420 и 112/420
5. (х+24,3):18,3=3,1, х+24,3=3,1*18,3=56,73, х=56,73-24,3=32,43