Where's the father? Some algebra required.

Feeling abit mathematical today, so here's a twist of a Standard 6 question:

The mum is 21 years older than the child. In 6 years from now the mum will be 5 times as old as the child.

The Question is: Where's the father??
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Think you have the answer?
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The mum (M) is 21 years older than the child (C).
M = C + 21

In 6 years from now the mum will be 5 times as old as the child.
M + 6 = (C + 6) x 5

Hence,
C + 21 + 6 = (C + 6) x 5
C + 27 = 5C + 30
-3 = 4C
C = -3/4

The child is negative 3/4 years old, it's still in the making,
it'll be born in 9 months….
So right now, the father is on top of the mother.