The second scale is 3 times the first scale:
300, 000 / 100,000 = 3
Divide the distance by the same scale factor:
12 cm / 3 = 4 cm
Check:
The scale 1 / 100,000 means 1 cm = 1 km, so at 12 cm the cities are 12 km apart.
The second scale 1 / 300000 means 1 cm = 3 km, since the cities are 12 km apart, divide total distance by scale: 12/3 = 4 cm.
850$ = X
Cost of ring = Y
X= (Y x 2) + 50
850= (Y x 2)
900=Y x 2
450 = Y
Answers:
Equation is 
Center is (-1, -2)
Radius = 5
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Work Shown:

center = (h,k) = (-1,-2)
radius = 5
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Explanation:
I grouped up the x and y terms separately. Then I added 1 to both sides to complete the square for the x terms. I cut the 2 from 2x in half, then squared it to get 1. In the next step, I cut the 4 from 4y in half to get 2, which squares to 4. So that's why I added 4 to both sides to complete the square for the y terms.
Each piece is factored using the perfect squares factoring rule which is a^2+2ab+b^2 = (a+b)^2
The last equation is in the form (x-h)^2 + (y-k)^2 = r^2
We can think of x+1 as x - (-1) to show that h = -1
Similarly, y+2 = y-(-2) = y-k to show that k = -2
The center is (h,k) = (-1,-2)
The radius is r = 5 because r^2 = 5^2 = 25 is on the right hand side in the last equation above.
Answer:
1/2
Step-by-step explanation:
Paso Uno:
* 1/10= 5/10
Paso Dos: Simplificar:
5/5=1
10/5=2
Paso Tres: fracción es 1/2