a paini albe, b semialbe, c negre
a+b+c=780 paini albe, semialbe, negre
b=c+25 paini semialbe cu 25 mai mult decat negre
a=c+125 paini albe cu 125 mai mult decat negre
Inlocuim in prima relatie
c+125+c+25+c=780
3c+150=780
3c=630,c=210 paini negre
b=210+25=235 paini semialbe
a=210+125=335 paini albe