Regression of x on y is 4x-3y=8

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Homework Statement



given the regression of y on x is 2y-3x=10 and the regression of x on y is 4x-3y=8 find the correlation r between x and y, also find the mean of x and the mean of y.

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The Attempt at a Solution


I am absolutley clueless on this problem, there is nothing in the book on how to do it, and every other time I have had to find the correlation I had some data set to work with. I am very confused.
 
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When you computed a regression equation from a sample of data, you had to compute the mean and variance of X and Y and their covariance in order to get the coefficients of the equation. In this problem, you are given the coefficients of the equation and asked to find the means and the correlation (which you can find from the covariance and variances). So you need to look up the way that you computed the regression equation from data and see how the slope and intercept are expressed as functions of the mean, variance and covariance of X and Y.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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