$$(50-10)\div 2=20$$ 
White and White Jr. have $$50$$ apples in total, and White has $$10$$ more appled than junior, so White Jr has~\uline{~~~~~~~~~~}~apples． 
Options:
(a) $$15$$ 
(b) $$20$$ 
(c) $$40$$ 
(d) $$60$$ 