Which term of the AP : 3, 8, 13, 18, . . . , is 78?

Explanation

Here, `a = 3, d = 5 and a_n = 78`

We know, `a_n = a+(n-1)d`

`=>78 = 3+5(n-1)=>n-1 = 15`

`=>n=16`

So, `16^(th)` term is the required term.