\(\begin{array}{l}3.8:2x = \frac{1}{4}:2\frac{2}{3}\\24:2x = \frac{1}{4}:\frac{8}{3}\\24:2x = \frac{3}{{32}}\\\,\,\,\,\,\,\,\,2x = 24:\frac{3}{{32}}\\\,\,\,\,\,\,\,\,2x = 24 \times \frac{{32}}{3}\\\,\,\,\,\,\,\,\,2x\, = \,\,\,256\\\,\,\,\,\,\,\,\,\,\,\,x = 256:2\\\,\,\,\,\,\,\,\,\,\,\,x = 128\end{array}\)