The price of 10 chairs equals that of 4 tables. If 15 chairs and 2 tables cost Rs. 4,000, find the total cost of 12 chairs and 3 tables.

Given data

• Let chair price = c, table price = t.
• 10c = 4t ⇒ t = (5/2)c = 2.5c.
• 15c + 2t = 4000.

Concept / Approach

• Express t in terms of c; solve for c from the total, then compute the required combination.

Step-by-step calculation
15c + 2(2.5c) = 4000 ⇒ 15c + 5c = 20c = 4000c = 200; then t = 2.5 × 200 = 500Required: 12c + 3t = 12×200 + 3×500 = 2400 + 1500 = 3900

Verification
10c = 2000 and 4t = 2000, consistent with 10 chairs = 4 tables.

Final Answer
Rs. 3,900