:
, :
1. . , , . 1, 2 3. 40 . m =20 / 2 , , .. . , . , 1 3 , .
2. :
(1-2) 1 2 ;
(2-3) 2 3.
3. .
4. 1, 2 3 , .
5. , .
6. (1-2), . 1 =10 . , . .. , , , .
7. (2-3) . 2 , 1. 10 2 20 . 30 . .. (2-3) , . 1 2 30 , .. . (2-3) 10 . 3, (2-3), () 10 , .. . , , , .