I don’t think I just want points
There are no numbers for this, thus you will have to use the quadratic formula.
The answer would be 24pi inches.
You can find this by using the formula for a circumference and plugging in the value of the radius.
C = 2pi*r
C = 2pi * 12
C = 24pi
This is a ratio problem; the ratio of the length to width is constant (and therefore equal):
4 /6 = 15 / x
Now, with a ratio, we may do any allowable algebra operation: cross-multiply, invert both sides, multiply or divide both sides by the same amount, etc.
Let's cross-multiply:
4x = (15)(6)
x = 90/4
x = 22.5 in.