1) Calcule as somas algébricas:
a) – 10 – 6 + 3 =
b) + 8 – 7 – 2 =
c) – 4 – 2 + 1 + 3 =
d) + 8 – 2 + 5 – 1 =
e) + 4 – 5 =
f) – 9 + 20 =
g) – 3 – 6 =
h) + 23 + 21 =
i) + 30 – 10 =