What is the ratio of the circumference to the diameter is

circle are all similar , and " the circumference divided by the diameter " produces the same value regardless of their radius . this value is the ratio of the circumference of a circle to it's diameter and called r (pi)

This question is asking only for the slope of the regression equation. This slope can be easily calculated using the following rule:
slope = SP / SSx

Examining the givens, we will find that both parameters are given where:
SP = 30 and SSx = 10

Substituting with the givens in the above mentioned equations, we can calculate the slope as follows:
slope = 30 / 10 = 3