A loss of 20% gets converted into a profit of 15% when the selling price of an article is increased by Rs. 70. Find the cost price of the article = ?

$$\eqalign{ & {\text{Let selling price}} = {\text{100}} \cr & \underbrace {\mathop {{\text{Loss}}}\limits_{80} \,\,\,\,\,\,\,\,\mathop {{\text{Profit}}}\limits_{115} }_{{\text{Selling price }}35} \cr & {\text{35}} \to {\text{70}} \cr & {\text{1}} \to \frac{{70}}{{35}} = 2{\text{ }} \cr & \therefore {\text{Cost price}} = 100 \times 2 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {\text{Rs}}{\text{. }}200 \cr} $$