Question

if a=5,d=3 and an=80 then n=
A. 26
B. 25
C. 20
C. 29​

Answer 1

Answer:

given, a(n) = 80, a = 5 and d = 3

to find n

An = a + (n-1)d

=> 80 = 5 + (n-1)*3

=> 80 = 5 + 3n - 3

=> 80 = 2 + 3n

=> 3n = 78

=> n = 78/3

=> n = 26