What is the 3rd term of this linear sequence
7, 9, 11, 13, 15

As we can see, what we are doing is substracting 4 from one term to the next:

22 - 4 = 18

18 - 4 = 14

14 - 4 = 10

10 - 4 = 6

Knowing this and that we start on 22, we can say that for n term we have:

So, if we're searching the thirs term, we replace n by 3 (we can also see it in the question):

=

So the third term is 14.