Fractions all sorts

The bottom half of a fraction is named the

 $\frac{1}{2}-\frac{4}{9}=$  

 $\frac{3}{5}\times\frac{10}{15}=$  

 $2\frac{1}{3}\times\frac{1}{7}=$  

 $\frac{2}{8}\div\frac{1}{3}=$