Let the numbers be x11 and y13
Now,
x11+y13=7143
=>13x+11y143=7143
=>13x+11y=7
Now, both x and y should be integers as denominator should be 11 and 13
Now,
13x+11y=7
=>y=7−13x11
By, hit and trial, we find x=9 will give y=−10 and there can be many other solutions.
Therefore, the rational numbers are 911 and −1013