\(0.1x + 0.5 = 0.8\)

$$\begin{align}
& 0.1x + 0.5 = 0.8 \\
& 1x + 5 = 8 \\
& x = 3
\end{align}$$

\(0.13 + 0.26x = 0.65\)

$$\begin{align}
& 13 + 26x = 65 \\
& 26x = 52 \\
& x = 2
\end{align}$$

\(3(0.24x - 0.12) + 0.15 = 1.95\)

$$\begin{align}
& 3(0.24x - 0.12) + 0.15 = 1.95 \\
& 0.72x - 0.36 + 0.15 = 1.95 \\
& 72x - 36 + 15 = 195 \\
& 72x - 21 = 195 \\
& 72x = 216 \\
& x = 3
\end{align}$$

\(\dfrac{2}{3}x = 8\)

$$\begin{align}
& \dfrac{2}{3}x = 8 \\[1em]
& 2x = 24 \\[1em]
& x = 12
\end{align}$$

\(\dfrac{5}{8}x + 4 = 14\)

$$\begin{align}
& \dfrac{5}{8}x + 4 = 14 \\[1em]
& \dfrac{5}{8}x = 10 \\[1em]
& 5x = 80 \\[1em]
& x = 16
\end{align}$$

\(\dfrac{1}{3} + 2x = \dfrac{2}{5}\)

$$\begin{align}
& \dfrac{1}{3} + 2x = \dfrac{2}{5} \\[1em]
& 5 + 30x = 6 \\[1em]
& 30x = 1 \\[1em]
& x = \dfrac{1}{30}
\end{align}$$

\(\dfrac{x}{2} + 5 = \dfrac{1}{4}\)

$$\begin{align}
& \dfrac{x}{2} + 5 = \dfrac{1}{4} \\[1em]
& 2x + 20 = 1 \\[1em]
& 2x = -19 \\[1em]
& x = \dfrac{-19}{2}
\end{align}$$