Can someone explain this to me please ?

Step-by-step explanation:
[tex]\text{We solve this with the help of laws of indices.}[/tex]
[tex]1.\ a^m\times a^n=a^{m+n}[/tex]
[tex]2.\ (a^b)^c=a^{bc}[/tex]
[tex]\text{So coming back to our original problem,}[/tex]
[tex](2^9\times 3^5)\times(2^4\times3)^2\\[/tex]
[tex]=(2^9\times3^5)\times(2^{4\times2}\times3^2)[/tex]
[tex]=2^9\times3^5\times2^8\times3^2\\[/tex]
[tex]=2^{9+8}\times3^{5+2}\\[/tex]
[tex]=2^{17}\times3^7[/tex]