Which term of the sequence 72, 70, 68, 66,... is 40?

Explanation

Also, we can see that the first term of the AP is 72. So, a = 72.

Now, we need to find the term whose value is 40 which means we need to find n if an=40.

As we know, that in an AP, a_n=a+(n−1)d.

So putting in the values we get:

40=72+(n−1)(-2)
40=72−2n+2⇒2n=34⇒n=17.

Here 17th term of the given AP is 40.