Let Herbie\textquotesingle s age this year be $$h$$ years. Then Gareth\textquotesingle s age this year is $$7h$$ years. In $$6$$ years\textquotesingle{} time, their ages will be $$h+6$$ years and $$7h+6$$ years respectively. We are told that $$7h+6=$$$$4$$$$\left(h+6\right)$$. This gives $$7h+6=4h+24$$ so that $$3h=18$$ and $$h=6$$.  So the present ages are $$6$$ and $$7\times 6=42$$, giving a difference of $$36$$ years. 
This year Gareth is seven times the age of his son Herbie. In six years\textquotesingle{} time Gareth will be four times as old as Herbie. What is the difference between Gareth\textquotesingle s and Herbie\textquotesingle s ages this year? 
A: $$16$$ years 
B: $$20$$ years 
C: $$24$$ years 
D: $$36$$ years 
E: $$42$$ years 