1)7x+3=20-2x
7x+2x=20-3
9x=17
x=17/9
x=2+8/9
Х поле
3/7Х+2/5Х=(29/35)Х за два ня
Х-29/35Х=6/35Х третий день = 72га
Х=72:6/35=432га поле
<span>1)
18 * (1/3 - 1/9) = 18*1/3 - 18*1/9 = 6 - 2 = 4,
2)
(2 - 3/4 - 4/5) * 20 = 2*20 - 20*3/4 - 20*4/5 = 40 - 15 - 16 = 9,
3)
(1 - 1/3 - 1/6 - 1/9) * 18 = 1*18 - 18*1/3 - 18*1/6 - 18*1/9 = 18 - 6 - 3 - 2 = 7,
4)
(5/6 + 5/9) * 18/25 = 5/6*18/25 + 5/9*18/25 = 3/5 + 2/5 = 5/5 = 1</span>
13 + 22 = 35
35/5=7
6*4-24
60-7=53
53-24=29
29+25=54
Ответ: 54