A man is 5 years older than his wife and the wife is now thrice as old as their daughter, who is 10 years old. How old was the man when his daughter was born
The daughter is currently 10 years old, and if the wife is three times her age, then the wife is 3 * 10 = <<3*10=30>>30 years old.
If the wife is 30 years old currently, she was 30 - 5 = <<30-5=25>>25 years old when the man was born.
So, the man is 30 - 25 = <<30-25=5>>5 years older than his wife.
Therefore, the man was 25 - 5 = <<25-5=20>>20 years old when his daughter was born. Answer: \boxed{20}.