oblicz : 3 i 3/8 - 5/8 =2 ../8-5/8
b 2 i 3/7 - 4/7 =1../7-4/7
c 8 i 2/5 - 4/5 =7../5-4/5
d 6 i 5/9 - 8/9=5.../9-8/9
