Question

- - = +
- + = -
+ - = -
+ + = ?​

Answer 1

- × - = +

- × - = -

+ × - = -

+ × + = +

Hope it helped u

Answer 2

$\huge\dag\tt{\red{\underline{Answer}}}\dag$

$( - ) \: ( - ) = + \\ ( + ) \: ( + ) = +$

As per the terms of signs 2 signs which are similar to each other are known as Positive Signs.

And 2 signs which are different from each other are known as Negative Signs.