(1/4+2/5)/(3/4 х - 1/2)=1/2
2(5/20+8/20)=3/4 х - 1/2
3/4х -1/2=13/10
3/4 х=13/10 +1/2
3/4 х=13/10+5/10
3/4 х=18/10
3/4 х=9/5
х=9/5 :3/4
х=9/5 * 4/3
х=12/5
х=2 2/5
<span>801020-х=6345
х=</span>801020-6345
х= 794675
<span>Ответ: х= 794675
</span><span>(6000-х)-1980=3800
</span>6000-х-1980=3800
4020-х=3800
х=4020-3800
х=220
<em>Ответ: х = 220 </em>
Ответ:
1) 4+7=11 ; 2) S=1/2•4•11=22см^2