Let Mary's age be x.
Paul is three times as old as Mary, so Paul's age would be 3x.
Peter is four times as old as Mary, so Peter's age would be 4x.
The sum of their ages is 64
⇒ Paul's age+ Peter's age+ Mary's age= 64
⇒ 3x+ 4x+ x= 64
⇒ 8x= 64
⇒ x= 64/8
⇒ x= 8
Paul's age is: 3x= 38= 24
Peter's age is: 4x= 48= 32
Final answer: Paul is 24 years old.
Peter is 32 years old.
Mary is 8 years old.
Hope this helps~
