very difficult exercise (with solution)

Mum is 21 year older than her son. After 6 years she will be 5 times older than her son. Where is dad?

Son's age - x
mum's age - x + 21
son's age after 6 years - x + 6
mum's age after 6 years - 5(x + 6)

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

-3/4 years = -9 months which leads us to the solution that dad is on mum.

Originally posted by kbaumen
Where is dad?

Originally posted by SwissGambit
Driving home from the sperm bank, hoping the donation was truly anonymous.

Originally posted by kbaumen
Omg, this is a dual!

Originally posted by David113
A cook😠