a) a+b = 20 12,75+7,(3)=20,08(3) deci fals
b)a+b =20,05 12,75+7,(3)=20,08(3) deci fals
c) b*c=18,0(074) 7,(3)*2,4(5)=18,0(074) deci adevarat
d)b*c=17,885 7,(3)*2,4(5)=18,0(074) deci fals
e) b:c= 660 supra 221
7,(3) :2,4(5)=(73-7)/9 :(245-24)/90=66/9:221/90=66/9x90/221 =660/221 deci adevarat
f)b:c=2,979 7,(3) :2,4(5)=660/221=2,986425.... deci fals
g)a-c =10,29(4) 12,75-2,4(5)=10,29(4) deci adevarat
H) a-c =10,3
12,75-2,4(5)=10,29(4) deci fals