I think:
(84 - 26) - 40 - (16 - 23) =
( 58 ) - 40 - ( -7 ) = [take care of sums inside parentheses]
58 - 40 + 7 = [- - 7 = + 7 ]
(58 + 7) - (40) = [group positives with positives and negatives with negatives]
65 - 40 =
25
-------
96 - (10 - 29 - 2) =
96 - ( 10 - (29 + 2) ) = [group positives with positives and negatives with negatives]
96 - ( 10 - 31) =
96 - ( - 21) = [take care of sum inside parenthesis]
96 + 21 = [ - - 21 = + 21]
117
(84 - 26) - 40 - (16 - 23) =
( 58 ) - 40 - ( -7 ) = [take care of sums inside parentheses]
58 - 40 + 7 = [- - 7 = + 7 ]
(58 + 7) - (40) = [group positives with positives and negatives with negatives]
65 - 40 =
25
-------
96 - (10 - 29 - 2) =
96 - ( 10 - (29 + 2) ) = [group positives with positives and negatives with negatives]
96 - ( 10 - 31) =
96 - ( - 21) = [take care of sum inside parenthesis]
96 + 21 = [ - - 21 = + 21]
117
