We know that they have:
2 entrences
3 ways to chose (escalator,elevator and stairs)
8 gates
and again 3 ways to chose (escalator, elevator and stairway)
now you have to multiply it:

There are 144 different ways that Anita and Terry can go from street level to the trains:)
The sum formula for a geometric sequaence is:
sum(n) = a1(1-r^n)/1-r
Where n is the number of terms, a1 is the first term and r is the common ratio:
s(8) = 3(1-1/2^8) / (1-1/2)
s(8) = 3(1-1/256) / 1/2
s(8) = 2 253/256 / 1/2
s(8) = 765/128
The answer is C.
Answer:
A. (55 x 5) - (40 x 5)
Step-by-step explanation:
You are solving how much miles (further along) would the second car be after 5 hours.
The first car averages 40 miles per hour. 5 hours later, it will have averaged about 200 miles in 5 hours (40 x 5 = 200).
The second car averages 55 miles per hour. 5 hours later, it will have averaged about 275 miles in 5 hours (55 x 5 = 275)
Subtract: 275 - 200 = 75
The second car would have averaged 75 more miles than the first car.
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You want to find the monthly average over the past 6 months.
July: $78.56
August: $30.21
September: $81.20
October: $79.08
November: $66.18
December: $100.75
Add all of these up
(July) $78.56
(August) $30.21
(September) $81.20
(October) $79.08
(November) $66.18
(December) + $100.75
----------------------------------------------
(Total cost) $435.88
There are 6 months you are calculating for, therefore divide the total (combined) cost of 6 months with the total number of months (in this case, 6)
$435.88 (total cost of 6 months) ÷ 6 (months)
The average cost per month of over the past 6 months is $72.66.