a) x=(12,1-11,9):4+4,5
x=0,2:4+4,5
x=0,05+4,5
x=4,55
y=[(2,3+1,5)×12,5]:(2,05-1,25)
y=[3,8×12,5]:0,8
y=47,5:0,8
y=59,375
Ma:(x+y):2=(4,55+59,375):2=63,925:2
=31,9625
Ma=31,9625
b)x=[(3,15+4,05)×36,9]:[(17,5-10,3)×0,41)=
X=[7,2×36,9]:[7,2×0,41]=
X=265,68:2,952
X=90
Y=21,7×(11,8-4,5)=
Y=21,7×7,3=
Y=158,41
Ma=(X+Y):2=(90+158,41):2=248,41:2 =124,205
Ma=124,205