Olá!!!
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a) x + y = 6 + 5 = 11
b) y + z = 5 + ( -6 ) = 5 -6 = 1
c) x + z = 6 + ( -6 ) = 6 -6 = 0
d) x + y + z = 6 + 5 + ( -6 ) = 11 + ( -6 ) = 11 -6 = 5
e) x - y + z = 6 - 5 + ( -6 ) = 1 + ( -6 ) = 1 - 6 = -5
f) - y + x -z = -5 + 6 - ( -6 ) = 1 - ( -6 ) = 1 +6 = 7
g) z + x - y = -6 + 6 - 5 = 0 -5 = -5