[tex]\bf 3+12\times \cfrac{5}{(5+15)}\implies 3+12\times \cfrac{5}{\underset{\uparrow }{20}}\implies 3+12\times \cfrac{1}{4}\implies 3+\cfrac{\stackrel{\downarrow }{12\times 1}}{4} \\\\\\ 3+\cfrac{12}{4}\implies 3+\stackrel{\downarrow }{3}\implies 9[/tex]
