1. Se foloseste media ponderata
(400g*50 C+600 g*30 C)/(400+600)=38 C
2. Se foloseste media aritmetica
x1+x2+x3+x4+x5+x6+x7=7*23=161
x1+x2+x3+x4+x5+x6=22*6=132
132+x=161
x=132-161=29 ani
3. a+b+c=850
a+b=655 ⇒c=850-655=195 lei
b+c=540,50 ⇒a=850-540,50=309,50 lei
b=540,5-c=540,50-195=345,50 lei