Question

If the arithmetic mean of 17, 2a-b, 2b-c and 2c-a is 20 then the arithmetic mean
of a, b, c is?

answer is (3). 21

need explanation​

Answer 1

Answer:

a + b + c = 5*3 = 15

c + d + e = 8*3 = 24

Add those two equations

a + b + 2c + d + e = 15 + 24 = 39

Meanwhile, we know the average of a, b, c, d, e is 7, so

a + b + c + d + e = 7*5 = 35

Subtract this from the line above:

(a + b + 2c + d + e) - (a + b + c + d + e) = 39 - 35

c = 4

OA = (C)