Step-by-step explanation:
Given that,
A meal plan lets students buy $20 meal cards.
Each meal card lasts about 8 days.
Let us assume that y denotes number of days for a 20 dollar meal card i.e. $20 every 8 days.
Let x = number of $ for another day.
So,
[tex]y=\dfrac{8}{20}x+8[/tex]
[tex]y=\dfrac{2}{5}x+8[/tex]
Hence, this is the required equation.