Sпрямоугольника=2а+2b=2*12+2*7=24+14=38 кв.см.
Ответ:38 кв.см.
-2x-122/9=-1
-2x-122=9
-2x=9+122
-2x=131
x= -131/2=-65 1/2=-65,5
1.] 11/3=(11//3)
2.]<span>-(11//3)+(-2.25)=-(11//3)-2.25
</span>3.]<span>-(11//3)-2.25=-(71//12)</span>
3 11/20 + 2 19/30 = 3 33/60 + 2 38/60 = 5 71/60 = 6 целых 11/60
9 5/6 - 2 3/4 = 9 10/12 - 2 9/12 = 7 целых 1/12
3 3/10 - 1 7/15 = 3 9/30 - 1 14/30 = 2 39/30 - 1 14/30 = 1 25/30 = 1 целая 5/6