Answer
$\dfrac{4a}{a^{2}+2a-15}-\dfrac{12}{a^{2}+2a-15}=\dfrac{4}{a+5}$
Work Step by Step
$\dfrac{4a}{a^{2}+2a-15}-\dfrac{12}{a^{2}+2a-15}$
Evaluate the substraction of the two rational expressions:
$\dfrac{4a}{a^{2}+2a-15}-\dfrac{12}{a^{2}+2a-15}=\dfrac{4a-12}{a^{2}+2a-15}=...$
Factor the denominator and take out common factor $4$ from the numerator. Then, simplify:
$...=\dfrac{4(a-3)}{(a+5)(a-3)}=\dfrac{4}{a+5}$
