Question

Each of my daughters has as many brothers as sisters, but each of my sons has three times as many sisters as brothers. How many children do I have?

Answer 1

Lets assume number of daughters = x
and number of sons = y

each daughter has as many sisters as brothers so,
y = x - 1
x - y = 1 ----------- (1)

each son has 3 times as many sisters as brothers so,
x =3(y - 1)
x = 3y - 3
x - 3y = -3 ---------------(2)

Subtract (2) from (1),
-y + 3y = 1 - (-3)
2y = 4
y = 4/2 = 2

From (1),
x - y = 1
x - 2 = 1
x = 1 + 2 = 3

Daughters = x = 3
Sons = y = 2
Total children = 2 + 3 = 5