a - brazi
b - stejari
c - fagi
a + b + c = 784
a + b = 346
b + c = 438
inlocuim in a + b+ c = 784 , a + b = 346
346 + c =784
c = 784-346 = 438
in b + c = 438 unde c = 438
b + 438 = 438
b = 438 - 438 = 0
a + b = 346
a= 346 - b= 346 - 0 = 346
a - 346 - brazi
b - 0 stejari
c - 438 fagi