Answer:
Each card will have a value of $15 when they equal after 600 days which also is 20 30-day periods.
Step-by-step explanation:
Card1: [tex]85 - \frac{3.50}{30} x[/tex]
Card2: [tex]75 - \frac{3}{30} x[/tex]
x is number of days
[tex]85 - \frac{3.50}{30} x = 75 - \frac{3}{30} x[/tex]
2550 - 3.50x = 2250 - 3x
2550 - 0.50x = 2250
-0.50x = -300
x = 600 days
Card1: [tex]85 - \frac{3.50}{30} (600)[/tex]
85 - 70 = 15 dollars
Card2: [tex]75 - \frac{3}{30} (600)[/tex]
75 - 60 = 15 dollars
