Answer:
a. 20
b. $15
Step-by-step explanation:
We can say that [tex]x[/tex] represent the 30-day period, then we can write the next equation:
[tex]55-2x=45-1.5x[/tex]
Finding the [tex]x[/tex], we find the number of 30-day periods until the value of the cards will be equal, then:
[tex]55-2x=45-1.5x\\55-45=-1.5x+2x\\10=0.5x\\\dfrac{10}{0.5}=x\\\\20=x[/tex]
Then is needed a 20 30-day periods to have the cards with equal value.
Now to know the walue of each card we have:
[tex]55-2x\\55-2(20)\\55-40=15[/tex]
Then each card will have a value of $15