Two Variables · Challenge problem

Scores $x$ on test A have mean $50$ and standard deviation $10$; scores $y$ on test B have mean $50$ and standard deviation $10$; the correlation is $r = 0.6$. A student scores $70$ on test A. Her test B score is predicted with the least-squares line of $y$ on $x$. That predicted B score is then plugged into the least-squares line of $x$ on $y$. What value of $x$ comes out? Give a decimal.