a)
(1/2 +4/7 +5/14):(2 si 3/7)=[7+8+5)/14]:(7x2+3)/14=
(20/14):(17/14)=(20/14)x14/17=20/17
b)
26grd48'18'' x6=156grd288'108''=156grd{4grd48'}{1'48''}=
160grd49'48''
c)
(2/3)^5 :(2/3)^3 +1/2=(2/3)^2 +1/2=4/9 +1/2=(8+9)/18=17/18
d)
156grd34'30'' -28grd12'20''=128grd22'10''
