Mark is 18 years old. He has a little brother, John, who is 10 years younger. If John and Mark's parents are currently 5 times older than John, how old were they when Mark was born?
John is 8 years old because 18-10=<<18-10=8>>8 years old.
Their parents are currently 40 years old because 8*5=<<8*5=40>>40.
Therefore, they were 22 when Mark was born because 40-18 = <<40-18=22>>22 years old.
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