Question

which term of the ap 3,8,13,18,....88

Answer 1

let a=3

d=5, (8-3)=5

an=78

78 = a+(n-1)d

78=3+ (n-1)5

78=3+5n-5

78=-2 +5n

78+2=5n

80=5n

n=80/5

n=16

Answer 2

I think it is helpful...