Question

5 creioane si 3 pixuri costa 19 lei.3 creioane si 6 pixuri costa 24 lei.determ pretul unui creion

Answer 1

5a+3b=19

3a+6b=24   simplificam prin 3    a+2b=8

Notam:  a=8-2b                              

5(8-2b)+3b=19                 

40-10b+3b=19

40-7b=19                            5a+3x3=19

7b=40-19=21                      5a=19-9=10 

b=3 lei (pixuri)                     a=10/5=2 lei (creion)