Question

how to find the sequence then find the unknown term like 3/10 2/5 blank blank blank blank blak

Answer 1

What do you exactly want us to do?

Answer 2

find the answer

Answer 3

find what is blank is

Answer 4

given only two terms, it is possible to make up a variety of ways to get from one to the other.

However, since the two values are

3/10, 4/10

The easiest rule I can think of is just to add 1/10 to get the next term.