Odpowiedź:
a) 4/5
b) 2/3 x 5 + 3/5 x 3 = 10/15 + 9/15 = 19/15
c) 3/7 x 9 + 2/9 x 7 = 27/63 + 14/63 = 41/63
d) 2/4
e) 3/8 x 3 + 2/3 x 8 = 9/24 - 16/24 = -7/24
f) 1/5 x 13 + 3/13 x 5 = 13/65 - 15/65 = -2/65
