The B.G. on a sum due 3 years at 10 % is $ 180. The B.D.

Here , Rate = 10% , Time = 3 years , B.G. = $ 180

T.D. =	B.G. x 100	= $	180 x 100	= $ 600
	R x T		10 x 3

∴ Banker 's Discount ( B.D. ) = True discount + Banker 's Gain ( B.G. )
Banker 's Discount ( B.D. ) = $ (600 + 180) = $ 780.