\[3\frac{5}{12} - \left( - 1\frac{1}{3} \right) + \left( - 4\frac{3}{8} \right) =\]
\[= 3\frac{5^{\backslash 2}\ }{12} + 1\frac{1^{\backslash 8}}{3} - 4\frac{3^{\backslash 3}}{8} =\]
\[= 3\frac{10}{24} + 1\frac{8}{24} - 4\frac{9}{24} =\]
\[= 4\frac{18}{24} - 4\frac{9}{24} = \frac{9}{24} = \frac{3}{8}.\]