Question

There are three numbers of which first is thrice the second and second is double the third.The average of all three numbers is 21.Find the number.

Answer 1

let the 3 numbers be a,b,c
given:
a=3b
b=2c
so a=3(2c)
a=6c

average=a+b+c/3
21 =6c+2c+c/3
21=9c/3
21=3c
so c=7
b=2(7)
b=14
a=6(7)
a=42