A tangent to the circle $x ^ { 2 } + y ^ { 2 } = 144$ passes through the point $( 20,0 )$ and crosses the positive $y$-axis.
What is the value of $y$ at the point where the tangent meets the $y$-axis?
A 12
B 15
C $\frac { 49 } { 3 }$
D 20
E $\frac { 64 } { 3 }$
F $\frac { 80 } { 3 }$