15^n/[5^(n-2)*3^(n+2)] = 5^n*3^n/[5^(n-2)*3^(n+2)] = 5^n*3^n]=
= 5^(n-n+2)/3^(n+2-n) = 5²/3² = 25/9 = 2 7/9
15^n/[5^(n-2)*3^(n+2)] = 5^n*3^n/[5^(n-2)*3^(n+2)] = 5^n*3^n]=
= 5^(n-n+2)/3^(n+2-n) = 5²/3² = 25/9 = 2 7/9