\[\frac{c^{2} + 6c + 10}{c + 3} =\]
\[= \frac{c^{2} + 3c + 3c + 9 + 1}{c + 3} =\]
\[= \frac{c(c + 3) + 3(c + 3) + 1}{c + 3} =\]
\[= \frac{c(c + 3)}{c + 3} + \frac{3(c + 3)}{c + 3} + \frac{1}{c + 3} =\]
\[= c + 3 + \frac{1}{c + 3}\]