Annmarie spends= 1/2 rent
Annmarie spends= 1/5 food
Annmarie spends= 1/8 utilities
[tex]\frac{1}{2}+\frac{1}{5}+\frac{1}{8}=\frac{33}{40}[/tex]she spends 33/40 in those 3 expenses
[tex]\frac{40}{40}-\frac{33}{40}=\frac{7}{40}[/tex]she have have left for other expenses 7/40