Between 3/5 and 4/5 there exist infinite rational numbers & we know that rational numbers are fractions, whole numbers and decimals. 

Trick: To find "n" rational numbers between any two numbers, multiply & divide both by "n+1".

Example: If we need to find 5 rational numbers between 3/5 & 4/5, we multiply and divide both the numbers by 6 to obtain the set of rational numbers.

Hence, five rational numbers between 3/5 and 4/5 are: