Question

The average income of a,b and c is rs 12000 per month and average income of b,c and d is 15,000 per month. if the average salary of d be twice that of a, then the average salary of b and c is

Answer 1

average income of A, B and C. = 12000


average income of b,cand d= 15000

given that,
salary of d= twice of a
d=2a

hence, total salary of b,c and d = average salary of b,c and 2a.


a+b+c= 12000
b+c=12000-a....(1)


2a+b+c=15000
b+c=15000-2a.....(2)
hence,

$12000 - a = 15000 - 2a \\ \\ \\12000 - 15000 = - 2a + a \\ \\ - 3000 = - a \\ \\ a = 3000$

adding both

a+b+c+2a+b+c=
$a + b + c + 2a + b + c = 15000 + 12000$
3a+2(b+c)=27000. (putting value of a=3000)

3(3000)+2(b+c)=27000

9000+2(b+c)=27000

2(b+c)=18000

b+c=18000/2
b+c=9000


hope it helps u