Find an explicit formula for the arithmetic sequence
81,54,27,0,...

an = -27n + 108.

Step-by-step explanation:

The first term a1 = 81 and the common difference d = 54-81 = -27 . (Also 27 - 54 = -27 and 0 - 27 = -27).

The explicit formula is  

an = a1 + d(n - 1)

= 81 - 27(n - 1)

= -27n + 81 + 27

= -27n + 108.

addition

step-by-step explanation:

the final amount you will pay is $68.04.

the tip is determined by the pre-tax amount, so we calculate the tip based on the original bill, not after we've added sales tax.

to find the tip:

we can divide 54.00 by 100 to get 1% of 54. then we multiply that by 18.

54 / 100 = .54

.54 x 18 = 9.72

tip = 9.72$

to find the tax:

we can divide 54.00 by 100 to get 1% of 54. then we can multiply that by 8 to get 8%.

54 / 100 = .54

.54 x 8 = 4.32

tax= 4.32

now we can add the tip and tax to the bill to get our total.

54 + 9.72 + 4.32 = 68.04

total: $68.04

step-by-step explanation: