A gold necklace was sold for Rs 78200 at a profit of 15 %. Find its cost price?

Given:

Selling price of necklace = ₹ 78200 and Profit % = 15%

To find:

We have to find the value of the Cost price of the necklace.

Solution: 

Now, we know that:

$Profit\ \%\ =\ \frac{Selling\ price\ -\ Cost\ price}{Cost\ price} \ \times \ 100$

$15\ =\ \frac{78200\ -\ CP}{CP} \ \times \ 100$

$15CP\ =\ (78200\ -\ CP)\ \times \ 100$

$15CP\ =\ 7820000\ -\ 100CP$

$15CP\ +\ 100CP\ =\ 7820000$

$115CP\ =\ 7820000$

$CP\ =\ \frac{7820000}{115}$

$\mathbf{CP\ =\ 68000}$

So, the Cost price of the necklace is ₹68000.