3/5-1/7 , 5/3-4/9, 24/25-7/15 ,11/80-11/90
срочно даю 29 балов

3/5-1/7=21/35-5/35=16/355/3-4/9=15/9-4/9=9/9=124/25-7/15=72/75-35/75=37/7511/80-11/90=99/720-88/720=11/720