Răspuns:
[tex]\frac{3^{n+1} }{27^4} =\frac{9^n:3}{81^5} \\\\3^{n+1} *81^5=27^4*(9^n:3)\\\\3^{n+1} *(3^4)^5=(3^3)^4*3^{2n} :3\\\\3^{n+1} *3^{4*5} =3^{3*4} *3^{2n} :3\\\\avem.aceeasi .baza.calculam.exponentul \\\\n+1+20=12+2n-1\\\\21-11=2n-n\\\\n=10[/tex]
