Răspuns :
s+f+m=810 puieti
s+m=422 puieti
m+f=644 puieti
422+f=810
fagi=810-422=388 puieti
fagi=388 puieti
s+644= 810 puieti
s=810-644=166 puieti
stejari=166 puieti
f+s= 388+166=554
810-554=256 puieti
mesteceni=256 puieti
PROBA
388+166+256=810 puieti
s+m=422 puieti
m+f=644 puieti
422+f=810
fagi=810-422=388 puieti
fagi=388 puieti
s+644= 810 puieti
s=810-644=166 puieti
stejari=166 puieti
f+s= 388+166=554
810-554=256 puieti
mesteceni=256 puieti
PROBA
388+166+256=810 puieti
Notam a,b,c-nr nec.
a+b+c=810
a+b=422⇒a=422-b
b+c=644⇒c=644-b
Inlocuim in a+b+c=810,pe a si c
422-b+b+644-b=810(-b cu +b se reduc)
422+b+644=810
1066+b=810
b=1066-810
b=256(mesteacan)
Cum,a=422-b⇒a=422-256⇒a=166(stejari)
Cum,c=644-b⇒c=644-256⇒c=388(fag)
Verificare:166+256+388=810
a+b+c=810
a+b=422⇒a=422-b
b+c=644⇒c=644-b
Inlocuim in a+b+c=810,pe a si c
422-b+b+644-b=810(-b cu +b se reduc)
422+b+644=810
1066+b=810
b=1066-810
b=256(mesteacan)
Cum,a=422-b⇒a=422-256⇒a=166(stejari)
Cum,c=644-b⇒c=644-256⇒c=388(fag)
Verificare:166+256+388=810