Question

Daca 4 becuri de iluminat si 5 intrerupatoare electrice costa 34 lei iar 4 becuri de iluminat si un intrerupator electric coste 10 lei.Calculati pretul unui bec.

Answer 1

4b+5i=34 =>4b=34-5i
4b+i=10 =>4b=10-i
Egalam cele doua expresii :
34-5i=10-i
34-10=5i-i
24=4i =>i=6 lei
4b=34-5x6
4b=34-30
4b=4 =>b=1 leu