Answer: 
Step-by-step explanation:
The formula for finding the nth term of an arithmetic sequence is given as:

first term = -15
common difference = -6 - (-15) = 9
number of terms
substituting into the formula , we have :


Answer:
Each shirt cost $12
Step-by-step explanation:
First, we have to interpret this question and turn each to an equation, letting shirts represent the letter s and ties represent the letter t.
6 shirts and 3 ties cost $79.50 would be interpreted to 6s+3t=79.5 ,and 3 shirts and 2 ties cost $41 would be interpreted to 3s+2t=41
Hence we have two equations, and we solve them simultaneously.
6s+3t=79.5 (Equation 1)
3s+2t=41 (Equation 2)
We can either use the substitution method or the elimination method but for the sake of this question, we use the Elimination method.
6s+3t=79.5 (Equation 1)
3s+2t=41 (Equation 2)
We multiply equation 1 by 2 and we multiply equation 2 by 3, I'm prefer to eliminate the
2(6s+3t=79.5)
12s+6t=159 Equation 3
3(3s+2t=41)
9s+6t=123 Equation 4
We subtract equation 4 from equation 3.
12s+6t=159
9s+6t=123
12s-9s=3s
6t-6t=0
159-123=36
We therefore have
3s=36
Divide both sides by 3
s=36/3
s=12
One shirt cost $12
Answer:
3,2
Step-by-step explanation:
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In solving this problem we can consider Earth to be a sphere. When we have a circle, then we can use this formula to find arc length:

Where:
L= arc length (in this problem it is disance we need to travel)
R = radius of circle (in this problem it is equal to a radius of Earth)
C = angle we need to pass
We are told that two cities lie halfway around the world. If we fly to west this means angle is 180°.
This gives an arc length of:

If we want to fly to north we need to go to 90° northern latidtude and then back to 17° latitude. This means angle is:
C=2*(90-17)=2*73°=146°
This gives an arc length of:

We can see that flying north is shorter. It is shorter by:
12440.71 miles - 10090.8 miles = 2349.91 miles
Answer:
Correct answer of this question is 123