Aset of n = 15 pairs of x and y scores has ssx = set of n = 15 pairs of x and y scores has ssx = 10,ssy = 40, and sp = 30. what is the slope for the regression equation for predicting y from x?

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