27) [tex] \frac{5}{9} [/tex] = [tex] \frac{15}{27} [/tex]
This is because 5 x 3 is 15. Whatever you do to the top, you do to the bottom. 9 x 3 is 27.
31) [tex] \frac{5}{7} [/tex] = [tex] \frac{25}{35} [/tex]
This is because 7 x 5 is 35. So you times 5 by 5 too.
Hope this helped :)