Arjun is twice as old as Shreya. Five years ago, his age was three times Shreya's age. What are their present ages?
a) Arjun: 15, Shreya: 5
b) Arjun: 10, Shreya: 5
c) Arjun: 10, Shreya: 3
d) Arjun: 15, Shreya: 10