\(\dfrac{15}{x+2}=\dfrac{3^3+3}{10}\\ \Leftrightarrow\dfrac{15}{x+2}=\dfrac{27+3}{10}\\ \Leftrightarrow\dfrac{15}{x+2}=\dfrac{30}{10}\\ \Leftrightarrow\dfrac{15}{x+2}=3\\ \Leftrightarrow x+2=\dfrac{15}{3}\\ \Leftrightarrow x+2=5\\ \Leftrightarrow x=5-2\\ \Leftrightarrow x=3\)