Question

Please answer the why ? ​

Answer 1

Explanation:

as because the 15th term is the actual 14th term

see we an= a+(n-1)d

a15=a+14d

as n=15

I think this May be the correct reason

Answer 2

Answer:

first, observe the above three pictures very carefully (specially, the second picture)

In the second picture, you can see that, as we subtract 1 from the last term, we get second last term,

and similarly, when we subtract 2 from the last term we gets the third last term,

so from this you can observe that,

when we subtract n=1, from the last term then we gets 2nd last term,

when we subtract n=2, then we gets 3rd last term,

so, we have to find the the last 11th term, for that we have to subtract 10 from the last term.

If you observe these pictures carefully, and read the explaination properly, you will understand.

but still if you get any doubt, you can ask bro