=(-8)+8+(-5) (additive commutative law)

=(-8)+8+(-5) (additive associative law)

=0+(-5) (0 plus negative number equals negative number)

=-5 (.When a number is added to 0, it still gets this number)

When a=-2, b =-7 and c = 12, a+b a+b+c = 3；; a+(-b)+c= 17。

. . . I thought the same thing.