linear equation

Let there be x number of boys and y number of girls in the family, then

For each daughter, number of brothers i.e. y  is same as number of sisters x - 1, since we are talking about one daughter.

i.e. x = y - 1    ...(1)

and similarly for each son,

2(x -1) = y    ....(2)

We can write (1) as,

x -1 = y - 2

Using this in (2),

2(y-2) = y

2y - 4 = y

y = 4,

and hence x = 3.

Hence 3 sons and 4 daughters are in the Vijay's family.

Regards,

Team,

TopperLearning.