$$8+24=32=8\times 4$$  So, $$3\times 4=12$$ 
For the ratio of $$3:8$$, if the consequent increases by $$24$$, the antecedent should~\uline{~~~~~~~~~~}~. 
1) $$+24$$ 
2) $$\times 4$$ 
3) $$\times 24$$ 
4) $$+4$$ 