Question

18 carti de 50 de file si respectiv 80 de file au impreuna 1050 file .cate file sunt de fiecare fe/

Answer 1

50*a+80*b=1050
50*5+80*10=1050
250+800=1050

Answer 2

50*x+80*y=1050
x   +   y   =   18     | *50
Inmultesc a doua ec cu 50 si o scad din prima
50*x  +   50*y = 900
50x+80y-50x-50y=1050-900
30y=150 ⇒ y= 150:30 ⇒ y=5 ⇒ x=18-5=13
verificare 50*13+80*5= 650+ 400 =1050