3. $$ \frac{5}{c+3} + \frac{5c-2}{c^2+3c} = \frac{5}{c+3} + \frac{5c-2}{c(c+3)} = \frac{5c + 5c - 2}{c(c+3)} = \frac{10c-2}{c(c+3)} $$
Ответ: $$ \frac{10c-2}{c(c+3)}$$