Пж помогите 21 22 по матиматике дам 15 балов

21:

1) 8.5  - 1/3 = 17/2 - 1/3 = 51/6 - 2/6 = 49/6.

2) 4 1/9 + 1.8 = 37/9 + 9/5 = 185/45 + 81/45 = 266/45.

3) 1/9 * 0.12 = 1/9 * 12/10 = 12/90 = 2/15.

4) 6/7 : 0.6 = 6/7 : 6/10 = 6/7 * 10/6 = 10/7.