+743 Compute
\frac{1}{1 \times 4} + \frac{1}{4 \times 7} + \frac{1}{7 \times 12}
+104 \(\frac{1}{1 \times 4} + \frac{1}{4 \times 7} + \frac{1}{7 \times 12}\)
\(\frac{1}{4}+\frac{1}{28}+\frac{1}{84}\)
\(\frac{21}{84}+\frac{3}{84}+\frac{1}{84}\)
\(\mathbf{\frac{25}{84}}\)
.
