Net rate = 1/12 - 1/18 = 3/36 - 2/36 = 1/36. Time = 36 hours.

Relative speed = 40 + 50 = 90 km/h = 25 m/s. Total distance = 120 + 180 = 300m. Time = 300/25 = 12 seconds. [Recalc: 12 seconds should match option C. Time = 300/25 = 12 seconds]

Downstream speed = boat speed + stream speed = 15 + 3 = 18 km/h.

SI = (P × R × T)/100 = (1000 × 8 × 2)/100 = Rs. 160.

Profit = (1.40 × 0.90 - 1) × 100 = 1.26 - 1 = 0.26 = 26%

Original = 100. After 25% increase = 125. After 20% decrease = 125 × 0.80 = 100. Net change = (100-100)/100 = 0%. Wait, recalculate: 125 × 0.80 = 100. Actually net is 0%. Correction: 100 × 1.25 × 0.80 = 100. Let me verify: 100 → 125 → 100. Net = 0%. Rechecking: 1.25 × 0.80 = 1.00. Net change = 0%.

When a merchant sells goods at a loss, the selling price is reduced from the cost price by the loss percentage. We use the formula: \(\text{Selling Price} = \text{Cost Price} \times \left(1 - \frac{\text{Loss\%}}{100}\right)\)

Step 1: Identify the given information

- Cost Price (CP) = Rs. 2000

- Loss = 15%

Step 2: Apply the loss formula

When there is a loss of 15%, the selling price is 85% of the cost price:

Step 3: Simplify the percentage

Step 4: Calculate the selling price

Answer: The merchant sold the goods at Rs. 1700 (Option A)

SI = (P × R × T)/100 = (8000 × 7.5 × 4)/100 = 240000/100 = Rs. 2400

100 × 1.20 × 0.90 = 108. Net increase = 8%

Let number = x. 0.60x = 240. x = 240/0.60 = 400