Given the arithmetic sequence a1,a2,a3,a4 44, 51, 58, 65 what is the value of a39?

This is an arithmetic sequence because there is a common difference between terms, a constant found when subtracting the preceding term from any term in the sequence.  In this case the common difference is 7.

Any arithmetic sequence can be expressed as:

a(n)=a+d(n-1), a=initial value, d=common difference, n=term number

Here we have a=44 and d=7 so

a(n)=44+7(n-1)

a(n)=44+7n-7

a(n)=7n+37, so the 39th term is:

a(37)=7(37)+7

a(37)=266

I am assuming that 44 is the first term, not the 5th term...if 44 was the fifth term let me know and I will edit to reflect that...