.
The answer = which tutor @ankor found, is not the solution to the problem,
since the fraction is not reduced. I came to bring the correct answer and solution.
m + n = 100 ====> n = 100-m.
So the inequality < takes the form
<
5m < 100 - m
6m < 100
m < = 16.66...
m <= 16.
Now we should consider all the fractions with 0 <= m <= 16 and select maximal of that which IS REDUCED.
I did it using EXCEL. See the table below.
T A B L E
m 100-m -reduced or not Value of
16 84 No
15 85 No
14 86 No
13 87 Yes 0.149425287 <<<---=== The maximum value : the solution and the answer
12 88 No
11 89 Yes 0.123595506
10 90 No
9 91 Yes 0.098901099
8 92 No
7 93 Yes 0.075268817
6 94 No
5 95 No
4 96 No
3 97 Yes 0.030927835
2 98 No
1 99 Yes 0.01010101
ANSWER. The greatest possible such fraction is = 0.149425287.
Solved, answered, explained and completed.