Calcula.
a) 6+ [5+(7+2)]
b) 8+ [4-(3+5)]
c) 10- [6+ (2+7)]
d) 15- [2- (6-10)]
e) 15- [10- (8+4)]
f) 12- [7- (2-10)]
g) (-6) + [5+ (2- 12)]
h) (-7) - [3- (4-9)]
i) (2-10) + [5- (8+2)]
j) (12-3) - [1- (2-6)]
k) [9- (+5)] + [7+ (-10)]
l) [10- (-2)] - [5- (+12)]
m) [8- (6+4)] - (5-7)
n)