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
Di you leave out some parenthesis? This looks like 3x+17x+53, which is the same as 20x+53? That is not enough information to solve. however, if you meant one angle was 3x+17 and the other was x+53, just set the two equal to each other to solve for x, then plug that into one of the equations to find the measurement of the angle.
