Answer :
[tex] \frac{25}{26} * \frac{13}{15} = \frac{25~*~13}{26~*~15} = \frac{325}{390} = \frac{5}{6} [/tex]
[tex] \frac{25}{26} * \frac{13}{15} = \frac{5*5}{13*2} * \frac{13}{3*5} = \frac{(13*5)*5}{(13*5)*3*2} = \frac{5}{6} [/tex]