28+15+4.5=28+19.5=47.5
37.5 e suma totala pe care au cheltuit-o toti 3 .
37.5:3 = 12.5
12.5 e suma pe care fiecare a cheltuit-o
a= 28+12.5 => a= 40.5
b= 15+12.5 = > b = 27.5
c= 4.5+12.5 = > c= 17
a = 40.5
b=27.5
c=17
verificare 40.5+27.5+17 = 68+17 = 85