1) 1,25 + 5/6 = 5/4 + 5/6 = 15/12 + 10/12 = 25/12
2) 25/12 : 25/3 = 25/12 * 2/25 = 1/4
3) 1/12 + 1/15 = 15/180 + 12/180 = 27/180 = 3/20
4) 3/20 - 0,05 = 3/20 - 5/100 = 15/100 - 5/100 = 10/100 (или 0,1)
5) 0,1 : 0,2 = 0,5 (или 1/2)
6) 1/4 : 1/2 = 1/2 (или 0,5)
7) 1/2 - 3/7 = 7/14 - 6/14 = 1/14
8) 1/14 * 0,42 = 1/14 * 42/100 = 21/700 (или 0,03)