А) 83~80
448~450
599~600
9404~9400
7999~8000
б) 343~300
735~700
697~700
3027~3000
19961~19900
в) 34991~30000
58554~60000
199075~200000
999000~1000000
г) 39~49
95~90
7148~7000
9800034~10000000
Проведем высоту ВК ( см . рисунок)
ВС=2 клеточки
ВК=3 клеточки
AD=4 клеточки
S(трапеции)=(a+b)·h/2=(ВС+AD)·ВК/2=(2+4)·3/2=9
Ответ 9 кв. ед
<span><span>3952/280
</span><span>280 /14.1(142857)
------
</span><span>-1152
</span><span>1120</span><span>
--------
-320</span><span>
280
---------
</span><span>-400</span><span>
280</span><span>
-----------
-1200</span><span>
1120</span><span>
----------
-800</span><span>
560</span><span>
-----------
-2400</span><span>
2240</span><span>
----------
-1600</span><span>
1400</span><span>
----------
-2000</span><span>
1960</span><span>
---------------
4<span>0
</span></span></span>
38:2=19
19+6=25
72-18=54
25:5=5
54:9=6
8*2=16
64:16=4
4-7=-3
6+(-3)=3
19*3=57
57+5=62
62-14=48
Ответ: 48
1) 15*(a+2)= 6*(2a+7)
15a+30=12a+42
15a-12a=42-30
3a= 12
a=4
2) 12b-7*(b+4)= 26- 4b
12b-7b-28= 26-4b
5b+4b=26+28
9b= 54
b= 6
3) 5 * (3c + 2) = 8 * (9 - 2c)<span>
15c+10= 72-16c
15c+16c= 72-10
31c=62
c=2
4)</span><span>10k + 2 * (7k - 2 ) = 5 * ( 4k + 3 ) + 3k
10k+ 14k-4=20k+15+3k
24k-4=23k+15
24k-23k=15+4
1k=19
k= 19:1
k=19 </span>