Question

I want to know the answer of these questions and the questions are

Answer 1

2 + 7 = 9

6 + 4 = 10

2 + - 7 = -5

- 2 + 7 = 5

- 2 + - 7 = -9

6 + - 4 = 2

- 6 + 4 = - 2

- 6 + - 4 = -10