Odpowiedź:
4 1/3 - b = 1 5/7
- b = 1 5/7 - 4 1/3 = 1 15/21 - 4 7/21 = 1 15/21 - 3 28/21 = - 2 13/21
b = 2 13/21
6 3/10 + 3 4/5 - 3 2/5 + 3 1/2 = - 3 2/5 + 6 3/10 + 3 8/10 + 3 5/10 =
= - 3 2/5 + 12 16/10 = - 3 4/10 + 12 16/10 = 9 12/10 = 10 2/10 = 10 1/5
1 3/4 + ( 99 7/20 - 89 2/5) - 1 1/2 = 1 3/4 + (99 7/20 - 89 8/20) - 1 1/2 =
= 1 3/4 + (98 27/20 - 89 8/20) - 1 1/2 = 1 3/4 + 9 19/20 - 1 1/2 =
= 1 15/20 + 9 19/20 - 1 1/2 = 10 34/20 - 1 10/20 = 9 24/20 = 10 14/20 =
= 10 7/10