Answer:
thanks for the points i mean really. anways hope someone else can help
The general equation for computing the circumference of a circle is

, where C is the circumference, and d is the diameter. (You might also see the equation as

where r is the radius, because

)
Computing the circumferences of the two circles, we get:


.
To calculate the ratio of two numbers, we can divide one by the other. You can look at this as "How many times does the denominator fit in the numerator?"

So the circumference of the complex impact crater is 2 times greater than the circumference of the simple impact crater.
Length of arc = (15/360) * 2*3.14*20 = 5.23 ins
circumference of the circle = 2*3.14*24 = 150.72
angle at center from 10 ft arc = (10/150.72) * 360 = 23.89 degrees
7 times 30 is 210
answer: 30