## Basic College Mathematics (10th Edition)

$13\frac{7}{10}$
$6\frac{3}{5}$ + $7\frac{1}{10}$ = $6\frac{6}{10}$ + $7\frac{1}{10}$ (10 is the least common denominator) = $6$ + $7$ + $\frac{6}{10}$ + $\frac{1}{10}$ (adding whole part separately and fractional part separately) = $13$ + $\frac{6 + 1}{10}$ = $13$ + $\frac{7}{10}$ = $13\frac{7}{10}$ The estimate was 14, so the exact answer of $13\frac{7}{10}$ is reasonable.