15/15 = 1 (целое), примем за х
4/15 · х = 28 4/15 · х = 160 4/15 · х = 1224
х = 28 : 4/15 х = 160 : 4/15 х = 1224 : 4/15
х = 28 · 15/4 х = 160 · 15/4 х = 1224 · 15/4
х = 7 · 15 х = 40 · 15 х = 306 · 15
х = 105 х = 600 х = 4590
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Или так:
28 : 4 · 15 = 105
160 : 4 · 15 = 600
1224 : 4 · 15 = 4590
12
Пошаговое объяснение:
1) -13 * 2/7 = -26/7 = -3. 5/7
2) 9 * (-3/4) = -27/4 = -6. 3/4
3) 27 * 2/7 = 54/7 = 7. 5/7
4) 3 * (-3/4) = -9/4 = -2. 1/4
5) -3. 5/7 - (-6. 3/4) + 7. 5/7 - (-2. 1/4) - 1 =
-3.5/7 + 6. 3/4 + 7. 5/7 +
2. 1/4 - 1 =
-3. 20/28 + 6. 21/28 + 7. 20/28 + 2. 7/28 - 1 =
3. 1/28 + 7. 20/28 + 2. 7/28 - 1 =
10. 21/28 + 2. 7/28 - 1 =
12. 28/28 - 1 = 13 - 1 = 12
ответ: 12