1) 6 - 4 1/2 = 5 2/2 - 4 1/2 = 1 1/2
2) 1 1/2 : 0,03 = 3/2 : 3/100 = 3/2 * 100/3 = 50
3) 3 1/20 - 2,65 = 3 1/20 - 2 65/100 = 3 5/100 - 2 65/100 = 2 105/100 - 2 65/100 = 40/100 = 2/5
4) 2/5 * 4 = 8/5
5) 8/5 + 2/5 = 10/5 = 2
6) 50 / 2 = 25
7) 0,3 - 3/20 = 3/10 - 3/20 = 6/20 - 3/20 = 3/20
8) 3/20 * 1 1/2 = 3/20 * 3/2 = 9/40
9) 1,88 + 2 3/25 = 1 88/100 + 2 3/25 = 1 88/200 + 2 12/100 = 3 100/100 = 4
10) 4 * 1/80 = 4/80 = 1/20
11) 9/40 : 1/20 = 9/40 * 20/1 = 9/2
12) 25 - 9/2 = 50/2 - 9/2 = 41/2 ответ в скобках
13) 41/2 : 2 1/20 = 41 : 41/20 = 41/1 * 20/41 = 20