You are given an arithmetic progression (аn), the difference of which is 5.5, а1 = -6.9. Find a6.

Knowing the 1st term of the sequence a1 and the difference of the progression d, we find the 2nd term in this sequence:

a2 = a1 + d = -6.9 + 5.5 = -1.4.

Find the third member of this sequence:

a3 = a2 + d = -1.4 + 5.5 = 4.1.

Find the fourth member of this sequence:

a4 = a3 + d = 4.1 + 5.5 = 9.6.

Find the 5th member of this sequence:

a5 = a4 + d = 9.6 + 5.5 = 15.1.

Find the 6th member of this sequence:

a6 = a5 + d = 15.1 + 5.5 = 20.6.

Answer: a6 = 20.6.