Incepem cu a nota necunoscutele:
a-intrebari corecte
b-intrebari gresite
Facem :
[tex] \left \{ {{5a-3b=340} \atop {a+b=100}|*3}} \right. \ \textless \ =\ \textgreater \ \left \{ {{5a-3b=340} \atop {3a+3b=300}} \right. =\ \textgreater \ 5a+3a=340+300\ \textless \ =\ \textgreater \ 8a=640 [/tex]
[tex]8a=640 |:8 =\ \textgreater \ a=80[/tex]
El a raspuns la 80 intrebari corecte.
Aflam si b (cele incorecte)
a+b=100
=>80+b=100 =>b=20
Deci, a raspuns gresit la 20 intrebari
