17. Oblicz:
a) 1 i 6/7 + 2 i 5/6 =
b) 4 i 3/8 - 2 i 1/5 =
c) 7 i 2/9 - 3 i 2/5 =
d) 5/7 × 13/15 =
e) 3/8 ÷ 9/24 =
f) 2 i 3/7 × 10 i 1/2 =​