Multiply each term of $ \left( \color{blue}{4x+6}\right) $ by each term in $ \left( 4x+5\right) $.

$$ \left( \color{blue}{4x+6}\right) \cdot \left( 4x+5\right) = 16x^2+20x+24x+30 $$

Combine like terms:

$$ 16x^2+ \color{blue}{20x} + \color{blue}{24x} +30 = 16x^2+ \color{blue}{44x} +30 $$

Multiply each term of $ \left( \color{blue}{16x^2+44x+30}\right) $ by each term in $ \left( 4x+4\right) $.

$$ \left( \color{blue}{16x^2+44x+30}\right) \cdot \left( 4x+4\right) = 64x^3+64x^2+176x^2+176x+120x+120 $$

Combine like terms:

$$ 64x^3+ \color{blue}{64x^2} + \color{blue}{176x^2} + \color{red}{176x} + \color{red}{120x} +120 = 64x^3+ \color{blue}{240x^2} + \color{red}{296x} +120 $$

Multiply each term of $ \left( \color{blue}{64x^3+240x^2+296x+120}\right) $ by each term in $ \left( 4x+3\right) $.

$$ \left( \color{blue}{64x^3+240x^2+296x+120}\right) \cdot \left( 4x+3\right) = 256x^4+192x^3+960x^3+720x^2+1184x^2+888x+480x+360 $$

Combine like terms:

$$ 256x^4+ \color{blue}{192x^3} + \color{blue}{960x^3} + \color{red}{720x^2} + \color{red}{1184x^2} + \color{green}{888x} + \color{green}{480x} +360 = \\ = 256x^4+ \color{blue}{1152x^3} + \color{red}{1904x^2} + \color{green}{1368x} +360 $$