Пошаговое объяснение:
1.
а) 2/9 * 27/28 = 1/1 * 3/14 = 3/14
б) 5/24 * 18 = 5*18 / 24 = 90/24 = 3 18/24 = 3 3/4
2.
а) 1/12 : 1/6 = 1/12 * 6/1 = 6/12 = 1/2
б) 5/6 : 15 = 5/6 * 15 = 75/6 = 12 3/6 = 12 1/2
3.
а) 1 1/3 * 3 3/8 = 4/3 * 27/8 = 1/1 * 9/2 = 9/2 = 4 1/2
б) 2 1/3 : 2 4/5 = 7/3 : 14/5 = 7/3 * 5/14 = 1/3 * 5/2 = 5/6
4.
5 1/3 : х = 1 3/5
х = 5 1/3 : 1 3/5
х = 16/3 : 8/5
х = 16/3 * 5/8
х = 2/3 * 5/1
х = 10/3
х = 3 1/3
5.
60 * 2/5 = 120/5 = 24 - литра потратил
6.
120 : 3/4 = 120 * 4/3 = 480/3 = 160 - всего страниц в книге
7.
(3/7х - 5/6) * 1 2/3 = 2 1/2
3/7х - 5/6 = 2 1/2 : 1 2/3
3/7х - 5/6 = 5/2 * 3/5
3/7х - 5/6 = 3/2
3/7х = 3/2 + 5/6
3/7х = 9/6 + 5/6
3/7х = 14/6
3/7х = 7/3
х = 7/3 : 3/7
х = 7/3 * 7/3
х = 49/9
х = 5 4/9
8.
1) 320 * 0,25 = 80 (кг) - картошки
2) 320 * 0,20 = 64 (кг) - морковки
3) 320 - (80 + 64) = 320 - 144 = 176 (кг) - капусты
7 2/5, 3 36/50
Пошаговое объяснение:
1) 8 7/10 - (7 4/5 - а) = (8 7/10 - 7 4/5) + а = (8 7/10 - 7 4•2/5•2) + а = (8 7/10 - 7 8/10) + а = (7 17/10 - 7 8/10) + а = 9/10 + а
если а = 6 1/2,
то 9/10 + 6 1/2 = 9/10 + 6 1•5/2•5 =6 5/10 + 9/10 = 9/10 + 6 5/10 = 6 14/10 = 7 4/10 = 7 2/5
2) а - (9 3/50 - 5 7/25) = а - (9 3/50 - 5 7•2/25•2) = а - (9 3/50 - 5 14/50) = а - (8 53/50 - 5 14/50) = а - 3 39/50
если а = 7 1/2,
то 7 1/2 - 3 39/50 = 7 1•25/2•25 - 3 39/50 = 7 25/50 - 3 39/50 = 6 75/50 - 3 39/50 = 3 36/50
