3x3x3x5x5 is in nonstandard form. Please, use " ^ " to denote exponentiation:
3x^3x^3x^5x^5.
Noting that a^b*a^c = a^(b+c), rewrite 3x^3x^3x^5x^5 as 3x^(3+3+5+5) = 3x^16.
