1. 3,9*0,7 = 2,73
2,73*4,8 = 13,104
13,104*0,03 = 0,39312
0,91*5,4 = 4,914
4,914*0,032 = 0,157248
0,39312 : 0,157248 = 2,5
2. 3 1/3 : 10 = 10/3 : 1/10 = 1/3
2 1/6 : 3 25/100 = 13/6 : 325/100 = 13/6*100/325 = 1300/1950 = 130/195 = 26/39
1/3 + 26/39 = 13/39 + 26/39 = 39/39 = 1
1 : 125/100 = 1*100/25 = 4
2/13 *52/10 = 1/13*52/5 = 1*4/5 = 4/5
3*2/13 = 3/1*2/13 = 6/13
48/10*2/13 = 96/130
4/5 + 6/13 = (52+30)/65 = 82/65
82/65 + 96/130 = 260/130 = 2
4/2 = 2