The answer is 60.7 because 90-29.3=60.7
1/4 hour because since it took him 3/4 hr to milk 3 groups, it is reasonable to divide 3/4 by 3. So in 1/4 hour.
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.
$36 x 1.07 = $38.52
The cost will be $38.52
Tax on this is $2.52
You have to use the quadratic formula to solve this. The zeros of this quadratic are 2 + sqrt2/2 and 2 - sqrt2/2, which in "real" numbers is 1.707 and .2928