[tex]\frac{7}{10} =\frac{7*4}{10*4}=\frac{28}{40}[/tex]
[tex]\frac{3}{4} =\frac{3*10}{4*10} =\frac{30}{40}[/tex]
As you can see:
[tex]\frac{28}{40} <\frac{30}{40}[/tex]
[tex]\frac{7}{10} <\frac{3}{4}[/tex]