(), ' () , , . г , .
, +1=7 +4=10 , 6. г 2 = -4 2 +5 = 0 ( ), .
г -8=1 2=81 , -8=1 =9, 2 = 81 : 1 = 9 2 = -9.
,
1) , , .
, + 4 = 2 + 9<=> 2 + 9 = + 4.
2) - , , , .
, 2 + 7 = - 3<=>2 - = -7-3.
3) , , .
, +1=4 ( +1=4 4).
4) , , .
, + 2 = 5<=> + 2 + 7 = 5 + 7; 5 + 2 = 0<=>5 + 2- 2 = 0- 2.
5) - , , , .
, = 2<=> + 2=2 + 2;
3 + 5 = 8 + 5 <=> 3 = 8