Question

x + y = 15, y + z = 25, and x + z = 20
What is the average (arithmetic mean) of x,y and z ?

Answer 1

x+y+y+z+z+x/6
15+25+20/6 =60/6
10 is the average (arithematic mean)

Answer 2

Haseeb is right.
If you add 15+25+20=60 that will be equal to 2(x+y+z)
So 30=(x+y+z)
And for 3 numbers the average is (x+y+z)/3

Answer 3

10 Is the average (arithmetic mean).