Given that;
Adalyn uses 1/5 cup of blue paint for every 2/5 cup of red paint to make purple paint.
[tex]\frac{1}{5}\text{ cups of blue paint }\rightarrow\frac{2}{5}\text{ cups of red paint}[/tex]For 1 cup of red paint, the amount of blue paints Adalyn will use is;
[tex]\frac{1}{5}\text{ cups of blue paint }\rightarrow\frac{2}{5}\text{ cups of red paint}[/tex]