B. is reasonable because 9.2×4.8 = 44.16
The formula for calculating length is:

We can also write

or

Why it does not matter?
Let's assume we have 2 numbers, a and b.
When we perform a subtraction:

, we get another number

When we perform another subtraction:

, we get a number

When we raise

or

to the power of 2, the result is the same,

.
This question is a little unclear. y= 4x - 3 is already in slope-intercept form. If you use (2,-3), then it would look like -3 = 4(2) - 3...
Sara's results probably do have a higher mean, if we take into account how William is way more willing to pay 20 dollars. Honestly, I think you got your chosen answers right! Just my opinion, as someone inexperienced.