Answer:
Its 21+84
Step-by-step explanation:
53
6x3=18
8-3=5
6+1=7
7x5=35
35+18=53
I hope this helps!
given
n=9
a=1
d=3-1=2
now , by formula,
sn = n/2(2a+(n-1)d)
= 9/2(2×1+(9-1)×2)
=9/2×18
=81
