oganesbagoyan

Verified answer

6<x<8;
-2<y <3;    6+(-2)< (x+y) < 8+3 ;   ⇔ 4<(x+y) <11 ;
X----X
6<x<8;    6<x<8;
-2<y <3  ⇒  -3 < - y <2 ; 6+(-3)< (x-y) <8+2 ⇔3 <(x-y) <10 ;
X----X
- 12 <xy < 24 .