[tex]⟹ \: \cancel \frac{15}{27} = (3 \times 3 \times 3 \times 3 \times 3 ) \: (9 \times 9 \times 9)[/tex]
[tex] ⟹ \cancel \frac{15}{27} = 5(3) \times 9(3)[/tex]
[tex]⟹ \cancel \frac{15}{27} = \frac{5}{9} [/tex]
Therefore, when 15/27 is factorise using the method of prime factorization we'll get 5/9.