If percentage of profit made,when an article is sold for Rs.78, is twice as when it is sold for Rs.69, the cost price of the article is

Let cost price of watch = Rs. $$100x$$

When selling price = Rs. 69

=> Profit % = $$\frac{69-100x}{100x} \times 100 = \frac{(69-100x)}{x}$$

Similarly, Profit % when SP = Rs. 78 = $$\frac{(78-100x)}{x}$$

According to ques,

=> $$(\frac{78-100x}{x})=2 \times (\frac{69-100x}{x})$$

=> $$78-100x=138-200x$$

=> $$200x-100x=138-78$$

=> $$100x=60$$

=> $$x=\frac{60}{100}=0.6$$

$$\therefore$$ Cost Price = $$100 \times 0.6=Rs.$$ $$60$$

=> Ans - (D)