FERMAT 1997 Problem 9

Past Contests FERMAT FERMAT - 1997
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1

If 10\le x\le20 and 40\le y\le60, the largest value of \displaystyle\frac{x^2}{2y} is

Answer Choices
A. 5
B. \frac56
C. \frac{10}{3}
D. \frac54
E. 10