Answer
$\displaystyle \frac{1}{2}x^{2}-\frac{7}{10}x$
Work Step by Step
$ \begin{array}{rrrrrrr}
& \frac{3}{8}x^{2} & -\frac{1}{3}x & -\frac{1}{4} & \\
-[ & (-\frac{1}{8})x^{2} & +\frac{1}{2}x & -\frac{1}{4} & ]\\
\hline & & & & \\
= & (\frac{3}{8}+\frac{1}{8})x^{2} & +(-\frac{1}{5}-\frac{1}{2})x & +(-\frac{1}{4}+\frac{1}{4}) & \\
& & & & \\
= & \frac{4}{8}x^{2} & +\frac{-2-5}{10}x & +0 & \\
& & & & \\
= & \frac{1}{2}x^{2} & -\frac{7}{10}x & & \\
& & & &
\end{array}$