Given that, 22B + 24G = 160 --- (1)
We need to find B+G= ?

I used the back solving by plugging the answer choices:

If B+G=7 --- (2)
(2) * 22 -- 22B+22G=154 --- (3)

Solving 1 and 3 we get, G=3 and B=4 and it satisfies the given equation 1 and 2. However if you plug in B+G=5

22B + 22G=110 so solving with 1 we get, G= 25 since B+5=5 G cannot be 25 or B cannot be -ve. so 8 is ruled out and only 7 works.

C.)

-Deepak

Plug in the answer choices. Split 7 into 4 and 3.

(C)

plugging seems to be the best choice here..


i used a crude way to solve...

let x be age of all boys and y be age of all girls

then

taking ratio we get

x/y = 11/12

x+y
----- = 23 / 12
y

160
----- = 23/ 12
y

y = 83

now i have to find a number closest to 83 that is divisible by 24 i get 24*3=72

and 160-72= 88 which is 22*4

thus we get the age of individual boy nd girl

so 3+4=7

hope this helps

cheers.