Question

Trei vecini au plecat la piata. Primul a cumparat 6 kg faina si 5 kg malai platind 135000 lei, al doilea a cumparat 5 kg faina si 8 kg malai platind 150000 lei si primind rest 3 monede a 1000 lei fiecare. Al treilea a cumparat 39 kg produse si a platit 360000 lei. Cate kg de faina si cate kg de malai a cumparat al treilea?

Answer 1

a=pret faina
b=pret malai
6a+5b=135000    ⇒ b=(135000-6a)/5
5a+8b=150000-3x1000=147000
5a+8(135000-6a)/5=147000
25a+1080000-48a=735000
345000=23a
a=15000 lei kg faina
b=(135000-6*15000)/5=45000/5=9000 lei/kg malai

x=kg faina
y=kg malai
x+y=39   y= 39-x
15000x+9000y=360000
15000x+9000(39-x)=360000
15000x+351000-9000x=360000
6000x=9000
x=1,5 kg faina
y=39-1,5=37,5 kg malai