Correct Answer - Option 3 : Rs. 630

**Given **

Marked price of toy = Rs 770

Discount percent = 10%

**Formula used **

Marked price : cost price = 100 + profit% : 100 - discount%

**Calculation **

⇒ Marked price : Cost price = 110 : 90 = 11 : 9

⇒ Marked price = Rs 770

⇒ 11x = 770

⇒ x = 70

⇒ Cost price of toy = 9x = 9 × 70 = Rs 630

∴ the cost price of a toy is Rs 630