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Un set de tacamuri ( 6 linguri, 6 furculite, 6 cutite si 6 lingurițe ) costa 318 lei. cat costa fiecare piesa, daca un cutit si o furculita costa cu 7 lei mai mult decât o lingura si o lingurita, lingurita este cu 3 lei mai ieftina decât lingura ,iar lingura si furculita au acelasi pret?

Răspuns :

l=lingura
f=furculite
c=cutite
l1=lingurite

6l+6f+6c+6l1=318==>6l+6f+7l+7l1=318==>13l+6f+7l1=318==>13l+6l+7l1=318==>19l+7(l-3)=318==>19l+7l-21=318==>26l=318+21==>26l=339==>l=339/26=>l=13 lei

c+f=7+(l+l1)=>c+13=7+13+10==>c+13=30=>c=30-13=>c=17 lei

l1=l-3=>13-3=>l1=10 lei

l=f=>f=13 lei

V: 6*13+6*13+6*17+6*10=318 lei


a=lingura
b=furculite
c=cutite
d=lingurite

6a+6b+6c+6d=318==>6a+6b+7c+7d=318==>13a+6b+7d=318==>13a+6a+7d=318==>19a+7(a-3)=318==>19a+7a-21=318==>26a=318+21==>26a=339==>a=339/26=>a=13 lei

c+b=7+(a+d)=>c+13=7+13+10==>c+13=30=>c=30-13=>c=17 lei

d=a-3=>13-3=>d=10 lei

a=b=>b=13 lei

V: 6*13+6*13+6*17+6*10=318 lei