$#DUCK$
(81-35)-(65-13)- (7-19)
= 81 - 35 - 65 + 13 - 7 + 19
= (81 + 19) + ( -35 - 65) + (13 -7)
= 100 - 100 + 6
= 6
- (56-61+42) - (44-142)-161
= -56 + 61 - 42 - 44 + 142 - 161
= ( -56 - 44 ) + ( 61 - 161 ) + ( -42 + 142)
= -100 - 100 + 100
= -100
535-(481-65)-( 19 -50)
= 535 - 481 + 65 - 19 + 50
= ( 535 + 65 ) + ( -481 - 19 ) + 50
= 600 - 500 + 50
= 150