If 3/5 of sweets are red, the remaining sweets represent the
[tex]1-\dfrac{3}{5}=\dfrac{5}{5}-\dfrac{3}{5}=\dfrac{2}{5}[/tex]
of the total. So, 3/5 are red and 2/5 are blue.
The blue to red ratio is
[tex]\dfrac{2}{5}\div\dfrac{3}{5}=\dfrac{2}{5}\cdot\dfrac{5}{3}=\dfrac{2}{3}[/tex]
