Explanation:
To find the cost of painting the blackboard, we first need to calculate its area.
Length of the blackboard = 5m 20cm = 5.20m
Breadth of the blackboard = 3m 40cm = 3.40m
Area of the blackboard = Length x Breadth
Area = 5.20m x 3.40m
Area = 17.68 square meters
The cost of painting 1 square meter at the rate of Rs. 10 is Rs. 10. Therefore, the cost of painting 17.68 square meters is:
Cost = Area x Rate
Cost = 17.68 square meters x Rs. 10 per square meter
Cost = Rs. 176.80
Therefore, the cost of painting the blackboard at the rate of Rs. 10 per square meter would be Rs. 176.80.