Question

Un telefon si o tableta costa 1300 lei,iar 3 telefoane si 4 tablete costa 4400 lei. Ce pret are o tableta?

Answer 1

tel = a
tableta=b

a+b=1300=> a=1300-b
3a+4b=4400
3(1300-b)+4b=4400
3900-3b+4b=4400
b=4400-3900
b=500 lei costa o tableta

a=1300-500
a=800 lei costa un telefon

Answer 2

Tel+tab=1300
3Tel+4tab=4400 inmultim prima relatie cu -3 si o adunam la  adoua dispar Tel4400
-3tab +4tab=4400-3900=500⇒o tableta =500  ⇒un telefon =800 
raspuns  o tableta =500lei    cam scumpa