I think it's -39
18 + 3 = 21
1/2 + 12/18 = 9/18 + 12/18 = 21/18 = 7/6
Commutativity or Abelian property
25 plus 21 plus 19 is equal to 65.
The answer is 68. Simply add the numbers together arithmetically as you would for the problem two plus two. To check your work, a calculator is the best option.
-15.
18 + 3 = 21
1/2 + 12/18 = 9/18 + 12/18 = 21/18 = 7/6
Commutativity or Abelian property
21 + 21 = 42.
-21
-39
25 plus 21 plus 19 is equal to 65.
16 + 16 + 16 + 17 + 18 + 18 + 18 + 19 + 19 + 20 + 20 + 20 + 21 = 238
18
36
21