1. Determine the unknown number $\mathrm{x}$ from the proportion $\frac{5}{8}:\left(0.4-2-\frac{1}{2} x\right)=1.25:\left(3.8-2 \frac{1}{4} \cdot x+\frac{1}{2}\right)$.
First method:

$$
\begin{array}{ll}
\frac{5}{8}:\left(0.4-2-\frac{1}{2} x\right)=1.25:\left(3.8-2 \frac{1}{4} \cdot x+\frac{1}{2}\right) & \\
\frac{5}{8} \cdot\left(3.8-2 \frac{1}{4} \cdot x+\frac{1}{2}\right)=1.25 \cdot\left(0.4-2-\frac{1}{2} x\right) & 1 \text{ POINT} \\
\frac{5}{8} \cdot\left(\frac{19}{5}-\frac{9}{4} \cdot x+\frac{1}{2}\right)=\frac{5}{4} \cdot\left(\frac{2}{5}-2-\frac{1}{2} x\right) & 1 \\
\frac{19}{8}-\frac{45}{32} x+\frac{5}{16}=\frac{1}{2}-\frac{5}{2}-\frac{5}{8} x / \cdot 32 & 1 \text{ POINT} \\
76-45 x+10=16-80-20 x & 1 \text{ POINT} \\
-45 x+20 x=16-80-76-10 & 1 \text{ POINT} \\
-25 x=-150 /:(-25) & 1 \text{ POINT}
\end{array}
$$

$$
\text { POINT }
$$