stim ca |x|=x si |-x|=x
a) 20
b) 30
c) 20
d) 10
e) 2^8 : 2^6 - (2^2) = 2^(8-6) - (2^2) = 2^2 - 2^2 = 0
f) 3^2 : 3 - 3 = 3 - 3 = 0
