ЕУОБ ТАБУ
12/5-13/72
5/9+13/27
ПОМОГИТЕ ПЖЖ

12/5-13/72= (12*72)/5*72 - ( 13*5)/5*72=(  840 -65)/360=775/360=155/72

5/9+13/27= (5*3)/27 +13/27=28/27