a,A = 54 + ( - 37 + 10 - 54 + 67 )
A = 54 + ( - 37 ) + 10 - 54 + 67
A = [ 54 - 54 ] + [ ( - 37 ) + 67 ] + 10
A = 0 + 30 + 10
A = 40
b. B = 1+ 2 - 3 - 4 + 5 - 6 + 7 - 8 + .... - 79 - 80 + 81
B = (1 + 2 - 3 - 4) + (5 + 6 - 7 - 8) +...+ (77 + 78 - 79 - 80) + 81
B = ( - 4 ) + ( -4 ) +...+ ( -4 ) - 81
B = ( - 4 ) . 20 + 81
B = ( - 80 )+ 81
B = 1