What are the all the even permutations of (+/-1, +/-a, +/- b) with an even number of plus signs ?

Question

Same question for all the odd permutations with an odd number of plus signs.
Are both numbers equal ?

Answer 1

+++ O
++ - E
+ -+ E
+ - - O
- ++ E
- + - O
- - + O
- - - E
There are 8 permutations, 4 with an even number of plus signs, and 4 with an odd number of plus signs.