1. Marco, Zharko, and Darko collected stickers in an album. Together, they collected 1650 stickers. Zharko collected $\frac{2}{3}$ of the number of stickers Marco collected, and Darko collected $\frac{3}{8}$ of the number of stickers collected by Marco and Zharko together. How many stickers did each child collect?
Solution. If Marco collected $x$ stickers, then Jarko collected $\frac{2}{3} x$ stickers and Darko collected $\frac{3}{8}\left(x+\frac{2}{3} x\right)$ stickers. Therefore,

$$
\begin{aligned}
& x+\frac{2}{3} x+\frac{3}{8}\left(x+\frac{2}{3} x\right)=1650 \\
& x+\frac{2}{3} x+\frac{3}{8} x+\frac{1}{4} x=1650 \\
& \frac{24 x+8 x+9 x+6 x}{24}=1650 \\
& \frac{55 x}{24}=1650 \\
& x=720
\end{aligned}
$$

Thus, Marco collected 720 stickers, Jarko collected $\frac{2}{3} \cdot 720=480$ and Darko collected $\frac{3}{8}(720+480)=450$ stickers.