Answer is in the pic above. Theorems used:
Exterior angle theorem
Inscribed angle theorem.

Answer:
First term (a) =8
Common difference (d)= t2-t1
=12-8
=4
Now, sum of first 31th term (tn31) =n/2{2a+(n-1)d}
= 31/2{2×8+(31-1)4}
=31/2{16+(30×4)
=31/2(16+120)
=31/2×126
=31×63
Step-by-step explanation:
Similarly use 19 as (n) for the 19th term
Do they want me describe the step by step process or no???
Answer:
10 is the answer
Step-by-step explanation:
Beacause 2 * 5 =10
and 5*2=10