Commutativity or Abelian property
identity
-21 - - 39 = -21 + 39 = 39 - 21 = (+)18 . For double mathematical signs think = + = - = - = + If no sign is shown , read it as plus(+). For
7y + 18 = 39 Therefore, 7y = 39 - 18 = 21 y = 21/7 y = 3
y = 3.6 (18/5)
3+4m+5m=214m+5m=21-39m=18m=18/9m=2
identity
21
-21.
73
-39 + 18 = -21 it is the same as saying 18-39.
15
7y + 18 = 39 Therefore, 7y = 39 - 18 = 21 y = 21/7 y = 3
That is the property of identity.
y = 3.6 (18/5)
3+4m+5m=214m+5m=21-39m=18m=18/9m=2
The mathematical statement 31 plus 21 equals 52 as a total.
21+21+19+19=80