An item costing Rs. 840 was sold by a shopkeeper at a gain of 10% and it was again sold by the new buyer at a loss of 5%. Find selling price of the item is = ?

According to the question,
Cost price = Rs. 840
10% Profit on cost price
$$\eqalign{ & = \frac{{10}}{{100}} \times 840 \cr & = {\text{Rs}}{\text{. }}84 \cr & \therefore {\text{Selling price}} \cr & = 840 + 84 \cr & = {\text{Rs}}{\text{. 924}} \cr} $$
New buyer cost price
$$ = {\text{Rs}}{\text{. 924}}$$
5% loss on Cost price
$$\eqalign{ & = \frac{5}{{100}} \times 924 \cr & = {\text{Rs}}{\text{. }}46.2 \cr & {\text{Selling price}} \cr & = {\text{Rs}}{\text{. 924}} - 46.2 \cr & = {\text{Rs}}{\text{. }}877.80 \cr} $$