Step 1 :
After factoring out $ 2x $ we have:
$$ 30x^{4}+36x^{3}+20x^{2}+24x = 2x ( 15x^{3}+18x^{2}+10x+12 ) $$Step 2 :
To factor $ 15x^{3}+18x^{2}+10x+12 $ we can use factoring by grouping:
Group $ \color{blue}{ 15x^{3} }$ with $ \color{blue}{ 18x^{2} }$ and $ \color{red}{ 10x }$ with $ \color{red}{ 12 }$ then factor each group.
$$ \begin{aligned} 15x^{3}+18x^{2}+10x+12 = ( \color{blue}{ 15x^{3}+18x^{2} } ) + ( \color{red}{ 10x+12 }) &= \\ &= \color{blue}{ 3x^{2}( 5x+6 )} + \color{red}{ 2( 5x+6 ) } = \\ &= (3x^{2}+2)(5x+6) \end{aligned} $$