Solution #6: How Old Is My Daughter?
Let us assume my daughter is age x. We are told my daughter
is twice as old as my son, so that my son must be age x/2.
We are also told that I am twice as old as my daughter so my age is 2x.
In 22 years time my son will be (x/2 + 22) and I will be (2x + 22).
Since he will be half of my age at that time,
x/2 + 22 = 1/2 (2x+22)
Multiplying both sides by 2
x + 44 = 2x + 22
x = 22
My daughter is 22 years old.
Source: Longley-Cook, L. H.
Categories: Reasoning, Algebra