To find the rational number between 16 and 15, make the denominators same.
LCM of 5 and 6 is 30, so,
16=1×56×5=530
15=1×65×6=630
A rational number between 530 and 630 is 5.530=55300=1160.
Similarly, LCM of 7 and 8 is 56, so,
28=2×78×7=1456
27=2×87×8=1656
One of the rational numbers between 1456 and 1656 is 1556.
In the case of 18 and 28, denominators are already same.
So, a rational number between 18 and 28 is 1.58=1580=316 .
In the case of 35 and 65 also, denominators are already same.
So, some of the rational numbers between them are 45 and 55.