Answer:
Step-by-step explanation:
I assume the 8 is the question number and the sequence is
29,38,47...
This is an arithmetic sequence as any term minus the previous term is a constant, called the common difference, which in this case is 47-38=38-29=9. An arithmetic sequence has the form
an=a+d(n-1)
Where an=nth term, a=initial term, d=common difference, and n=term number.
In this case a=29 and d=9 so
an=29+9(n-1)
an=9n+20, then the 21st term is
a(21)=9(21)+20
a(21)=189+20
a(21)=209
So the 21st term is 209.
