Binom Formula [tex]\displaystyle (a+b)^n=\displaystyle \sum^{n}_{k=0}C^k_na^{n-k}b^k[/tex]
where [tex]a=3n;~~ b=4m[/tex] and we find the coefficient of the fifth term.
[tex]C^4_8(3n)^{8-4}(4m)^4=\dfrac{8!}{4!4!}\cdot 3^4\cdot n^4\cdot 4^4\cdot m^4=12^4\cdot70m^4n^4[/tex]
coefficient is equal to [tex]70\cdot 12^4=1451520[/tex]
