Question

Intr-o punga sunt bile de 3 culori . Dintre ele 1 supra 3 sunt rosii , 3 supra 4 din rest sunt albe iar cele 12 ramase sunt negre .Cate bile sunt de fiecare culoare ?

Answer 1

x=nr total bile
bile rosii=$\frac{1}{3} x$
bile albe=$\frac{3}{4} (x- \frac{1}{3} x)$
bile negre=12
$x= \frac{1}{3}x + \frac{3}{4} (x- \frac{1}{3}x )+12 \\ x= \frac{x}{3} + \frac{3x}{4} - \frac{x}{4} +12 \\ x= \frac{4x}{12} + \frac{9x}{12} - \frac{3x}{12}+ \frac{144}{12} \\ x= \frac{10x+144}{12} \\ 12x=10x+144 \\ 2x=144 \\ x= \frac{144}{2} \\ x=72$