You have a gift card for a coffee shop worth $90. each day you use the card to get a coffee for $4.10. write an explicit formula to represent the amount of money available as an arithmetic sequence. what is the value of the card after you buy your 8th coffee?

The value of the card after you buy your 8th coffee will be $61.3

Step-by-step explanation:

The worth of the gift card for the coffee shop is $90. Each day you use the card to get a coffee for $4.10. This means that the worth of the gift card is reducing by $4.10 each day. This rate is in arithmetic progression.

The formula for the nth term of an arithmetic sequence, Tn is expressed as

Tn = a + (n-1)d

Where a is the first term

d is the common difference

n is the number of days

From the information given,

a = $90

d = - $4.1

The explicit formula representing the amount of money available will be

Tn = 90 - 4.1(n - 1)

The value of the card after you buy your 8th coffee will be

T8 = 90 - 4.1(8 - 1) = T8 = 90 - 4.1×7

T8 = 90 - 28.7

T8 = $61.3