The angles of triangle are in A.P. whose common difference is 20°. Find angles.

-11, -7, -3, …….,49, 53 are the terms of a progression.

Answer the following:

(a) What is the type of progression?

(b) How many terms are there in all?

(c) Calculate the value of middle most term.

Find the sum :

9 + 7 + 5 + 3 +……to 14 terms.

Find the sum :

(-11) + (-7) + (-3) + 1 +……to 12 terms.