)
1/12 + 1/6 = 1/12 + 2/12 = 3/12 = 1/4
3/8 - 1/4 = 3/8 - 2/8 = 1/8
1/4:1/8 = 8/4 = 2
Ответ: 2
2)
7/9 - 2/3 = 7/9 - 6/9 = 1/9
1/3 + 2/15 = 5/15 + 2/15 = 7/15
1/9 : 7/15 = 15 / 63 = 5/21
Ответ: 5/21
3)
5/7 - 2/3 = 15/21 - 14/21 = 1/21
4/9 - 5/12 = 16/36 - 15/36 = 1/36
1/21 : 1/36 = 36/21 = 12/7
Ответ: 12/7
4)
1 - 7/10 = 10/10 - 7/10 = 3/10
2 + 1/4 = 8/4 + 1/4 = 9/4
3/10 * x = 9/4
x = 9/4 : 3/10 = 90/12 = 15/2 = 7,5
5)
3 + 1/8 + 1 + 3/4 = 4 + 1/8 + 3/4 = 32/8 + 1/8 + 6/8 = 39/8
2 + 1/6 = 12/6 + 1/6 = 13/6
39/8 * x = 13/6
x = 13/6 : 39/8
x = (13*8) / (6*39) = 8 / (6*3) = 4/9