General form of an AP

Q.

What does $N$ mean in math?

Q.

Identify the common difference of the given AP: a, a+d, a+2d, a+3d, ...

1. 0

2. -d

3. d

4. 2d

Q. In an arithmetic series, d = -4, n = 7 and a(n) is equal to 4, then what is the value of the term a(1)?

1. 7
2. 20
3. 28
4. 27