Answer:
[tex]3(4 {x}^{2} {y}^{3} + 2 {x}^{3}) - 4(9 {x}^{3} {y}^{2} - 6 {x}^{2} {y}^{3} ) \\ = (12 {x}^{2} {y}^{3} + 6 {x}^{3} ) - (36{x}^{3} {y}^{2} - 24{x}^{2} {y}^{3}) \\ = (12 {x}^{2} {y}^{3} + 6 {x}^{3} ) + ( - 36{x}^{3} {y}^{2} + 24{x}^{2} {y}^{3}) \\ = - 36{x}^{3} {y}^{2} + 36x^{2} {y}^{3} + 6 {x}^{3} [/tex]
I hope I helped you^_^
