MathNet 2011 Question 83

Let $m$ and $n$ be positive integers, such that $19 \le m \le 49$, $51 \le n \le 101$. What is the greatest possible value of the expression $\frac{n+m}{n-m}$?
(A) 20
(B) 30
(C) 40
(D) 50
(E) 60