Let the line of regression of y on x be 3x+12y=19 or ‌‌y=‌
−3x+19
12
and x on y be x=‌
−3y+46
9
∴ Regression coefficient of y on x is byx‌=‌
−3
12
‌=−‌
1
4
and regression coefficient of x on y is bxy‌=−‌
3
9
=−‌
1
3
∴‌ Correlation ‌rxy‌=−√byx×bxy (here, we take negative sign outside the square root, because both regression coefficients are negative) ‌=−√−‌