Question

intr-un concurs se pun 30 de intrebari.fiecare raspuns corect are 5 puncte.iar cel gresit se scad 3 puncte.elevul a obtinut 30 de puncte.cate raspunsuri gresite si cate corecte

Answer 1

$Test=30~probleme \\ x=probl.rezolvate~corect. \\ y=probl.~rezolvate~gresit. \\ x+y=30 \\ x=30-y \\ 5x-3y=30(punctele) \\ 5*(20-y)-2y=30 \\ 100-5y-2y=30 \\ 100-7y=30 \\ -7y=30-100 \\ -7y=-70 \\ y=-70:(-7) \\ y=10(probleme~rezolvate~gresit.) \\ x=30-10 \\ x=20(probleme~rezolvate~corect)$