1)13 - 89/10 =(13 × 10 - 89 × 1)/10 = (130 - 89)/10 = 41/10 = 4 1/10
2)6 1/2 - 15 1/5 = 53/2 - 76/5 = (53 × 5 - 76 × 2)/10 = (265 - 152)/10 = 113/10 = 11 3/10
3)14 1/5 - 7 = 71/5 - 7 = (71 × 1 - 7 × 5)/5 = (71 - 35)/5 = 36/5 = 7 1/5
4)3 3/10 + 8 1/2 = 33/10 + 17/2 = (33 × 1 + 17 × 5)/10 = (33 + 85)/10 = 118/10 = 59/5 = 11 4/5
5)4 1/10 + 11 3/10 = 41/10 + 113/10 = (41 + 113)/10 = 154/10 = 77/5 = 15 2/5
6)15 2/5 - 7 1/5 = 77/5 - 36/5 = (77 - 36)/5 = 41/5 = 8 1/5
7)8 1/5 + 11 4/5 = 41/5 + 59/5 = (41 + 59)/5 = 100/5 = 20
ответ 20