Question

Ana si Bogdan au impreuna 7 mere, iar Ana si Catalin au impreuna 8 mere. Determinati cate mere are Ana stiind ca, impreuna , cei 3 copii au 12 mere

Answer 1

Ana, Bogdan si Catalin au a, b, respectiv c mere.

a + b = 7
a + c = 8
a + b + c = 12

Daca aduna a + b si a + c, obtinem a + a + b + c = 15. Daca dupa scadem din acest rezultat a + b + c, obtinem a = 3

Answer 2

A+B=7 mere A+C=8 mere A+B+C=12 mere 7+C=12 C=12-7 C=5 A+B+C=12 8+B=12 B=12-8 B=4 A=12- (4+5) A=12-9 A=3