$$6$$ pens = $$5$$ pencils, we use $\times6$ which give us $36$ pens = $30$ pencils 
If $$6$$ pens cost as much as $$5$$ pencils, then $$36$$ pens cost as much as pencils. 

(1) $$6$$ 
(2) $$30$$ 
(3) $$21$$ 
(4) $$98$$ 