A wholesale club charges a membership fee of ₹1200 a year and then sells every item at 8% below the usual shop price. The smallest yearly purchase, measured at usual shop prices (in ₹), for which the membership just pays for itself is:

The saving is 8% of the usual-price total, and it must cover ₹1200: $0.08B=1200$ gives $B$ = ₹15000. At that level the member pays ₹13800 and saves exactly the fee — ₹13800 is the amount paid, not the usual-price total asked for. Multiplying by 8 gives ₹9600 and dividing by 0.8 instead of 0.08 gives ₹1500.