1.
7/8 * 64 = 7 * 8 = 56,
5/8 * 4/25 = 1/10,
5/8 * 9 1/7 = 5/8 * 64/7 = 40/7 = 5 5/7,
0,15 * 40 = 15/100 * 40 = 3 * 2 = 6,
0,65 * 3/13 = 65/100 * 3/13 = 15/100 = 3/20,
2.
32 * 5/8 = 4 * 5 = 20 кустов гортензии,
3.
1)
7 1/5 * 5/9 = 36/5 * 5/9 = 4 см - 2 сторона,
2)
Р = 2 * (7 1/5 + 4) = 2 * 11 1/5 = 2 * 56/5 = 112/5 = 22 2/5 см - периметр,
3)
S = 7 1/5 * 4 = 36/5 * 4 = 144/5 = 28 4/5 см² - площадь,
4.
1)
100% - 8% = 92% - процент содержания железа,
2)
360 * 0,92 = 360 * 92/100 = 1656/5 = 331 1/5 кг - железа,
1)
360 * 0,08 = 360 * 8/100 = 28 4/5 кг - меди,
2)
360 - 28 4/5 = 359 5/5 - 28 4/5 = 331 1/5 кг - железа,
5.
(5 2/5 - 1 5/6 + 3 4/15) * 2 2/5 - 3 2/3 = 12 11/15,
1) 5 2/5 - 1 5/6 + 3 4/15 = 5 12/30 - 1 25/30 + 3 8/30 =
= 4 42/30 - 1 25/30 + 3 8/30 = 6 25/30 = 6 5/6,
2) 6 5/6 * 2 2/5 = 41/6 * 12/5 = 82/5 = 16 2/5,
3) 16 2/5 - 3 2/3 = 16 6/15 - 3 10/15 = 15 21/15 - 3 10/15 = 12 11/15
тогда а-12х
с-4х
12х больше, чем 4х
в 12/4=3 раза