What is the sum of the first 21 terms of this arithmetic series?
-5+(-3)+(-1)+1+

Step-by-step explanation:

The given arithmetic series is

-5+(-3)+(-1)+1+...

The first term of this series is

The common difference is

The sum of the first n-terms of an arithmetic sequence is

The sum of the first 21 terms of this arithmetic series is 315.

Step-by-step explanation:

The given arithmetic series is

-5+(-3)+(-1)+1+...

Here first term is -5 and the common difference is

The sum of n terms of an AP is

We need to find the sum of the first 21 terms of this arithmetic series.

Substitute n=21, a=-5 and d=2 in the above formula, to find the sum of the first 21 terms of this arithmetic series.

Therefore the sum of the first 21 terms of this arithmetic series is 315.

b is 38 degrees.

a is 52 degrees.

this is because if b is 38 and a is 14 degrees more than b than 38+14=52 and 52+38=90 degrees. hope this .

$15 each

step-by-step explanation:

$45/3 children= $15 each