We know that
• Nathan spent 1/5 on a movie.
,• He spent 1/4 on a snack.
First, we add the money spent
[tex]\frac{1}{4}+\frac{1}{5}=\frac{5+4}{20}=\frac{9}{20}[/tex]Nathan spent 9/20 of his allowance.
Then, we subtract
[tex]\frac{1}{4}-\frac{1}{5}=\frac{5-4}{20}=\frac{1}{20}[/tex]