выполните деиствия 
1. 5/6*9/15-5/12*4/15  
2. 7/18*9/14+1/3*6/7
3. 9/20*2/3+5/14*7/25
4. 3.3/4*2/5-3.6/25*5/27
5. 2.2/5*5/6-3/4*1.2/3
6.  1.17/28*14/9+14/25*5/7