A school library had $$3900$$ books. The ratio of the number of Chinese, Malay and English books is $$4 : 3 : 6$$. When the school bought $$510$$ new books, the number of Chinese books increased by $$20$$\% and the number of Malay books increased by $$10$$\%. Find the percentage increase in the number of English books. 
Overseas Competition->Knowledge Point->Calculation Modules->Percentage Calculation