A room measures 15 meters in length, 4 meters in width, and 3 meters in height. Calculate the expense of whitewashing all four walls if the rate is 50 paise per square meter.

Explanation

The total area of the four walls is calculated as 2 × height × (length + width) = 2 × 3 × (15 + 4) = 114 m². At 50 paise (0.50 Rs) per square meter, the cost is 114 × 0.50 = Rs. 57.