Odpowiedź:
7 i 2/3 + 1 i 1/15 = 7 i 10/15 + 1 i 1/15 = 8 i 11/15
5 i 1/4 - 2 i 7/8 = 5 i 2/8 - 2 i 7/8 = 4 i 10/8 - 2 i 7/8 = 2 i 3/8
3 i 1/3 : 1 i 1/2 = 10/3 * 2/3 = 20/9 = 2 i 2/9
4 i 2/3 * 2 i 4/3 = 14/3 * 10/3 = 140/9 = 15 i 5/9
2/3 liczby 42 = 2/3 * 42 = 28
