Given Information:
- Relation between x and u: 3x - 4u + 7 = 0
- Correlation coefficient between x and y: -0.6

Calculating the Correlation Coefficient between u and y:

To calculate the correlation coefficient between u and y, we need to find the relationship between u and y. We can do this by substituting the given relation between x and u into the equation of correlation coefficient between x and y.

1. Substitute the relation between x and u into the equation of correlation coefficient:
-0.6 = (cov(x,y)) / (σx * σy)

2. Find the covariance of x and y:
cov(x,y) = σx * σy * (-0.6)

3. Substitute the given relation between x and u into the covariance equation:
cov(x,y) = σx * σy * (-0.6) = (σx * σy * (-0.6)) / (σu * σy)

4. Simplify the equation by canceling out σy from both sides:
cov(x,y) = (σx * σy * (-0.6)) / (σu * σy)
cov(x,y) = (σx * (-0.6)) / σu

5. Substitute the relation between x and u into the equation of covariance:
cov(x,y) = (3σx - 4σu) * (-0.6) / σu

6. Simplify the equation by distributing the multiplication:
cov(x,y) = (-1.8σx + 2.4σu) / σu

7. Rearrange the equation to isolate the covariance term:
(-1.8σx + 2.4σu) = cov(x,y) * σu

8. Divide both sides of the equation by σu:
(-1.8σx + 2.4σu) / σu = cov(x,y)

9. Simplify the equation:
-1.8σx + 2.4 = cov(x,y)

Conclusion:

The correlation coefficient between u and y is -1.8σx + 2.4, which is determined by the relation between x and u.