A) - 20 + [ 15 - (7 - 12) + 4B) - [ 15 - ( 8 + 5 ) + ( 4 - 9 ) ] - 7C) - [ - { [ ( + 3 ) + ( - 2 ) ] - [ ( - 9 ) ] } ]D) 5 + 4 - [ ( - 4) - { ( + 7) - [ - ( - 3) - ( + 2) ] + ( - 4) } + ( + 6) ]POR FA?

Hola Lllaa,

A = - 20 + (15 - (7 - 12) + 4)

A = - 20 + (15 + 5 + 4)

A = - 20 + 24

A = 4

B = - (15 - (8 + 5) + (4 - 9)) - 7

B = - (15 - 13 - 5) - 7

B = - (2 - 5) - 7

B = 3 - 7

B = - 4

C = - ( - ((( + 3) + ( - 2)) - ( - 9)))

C = - ( - ((3 - 2) + 9))

C = - ( - (1 + 9))

C = - ( - 10)

C = 10

D = 5 + 4 - (( - 4) - (( + 7) - ( - ( - 3) - ( + 2)) + ( - 4)) + ( + 6))

D = 9 - ( - 4 - (7 - (3 - 2) - 4) + 6)

D = 9 - ( - 4 - (7 - 1 - 4) + 6)

D = 9 - ( - 4 - 2 + 6)

D = 9 - 0

D = 9.