Consider given the labour per hour 4 r.s
Now,
Labour of n hours =4×n =4n r.s
An electric heater is rated at 2 kW. Electrical energy costs Rs 4 per kWh. What is the cost of using the heater for 3 hours ?
(a) Rs 12
(b) Rs 24
(c) Rs 36
(d) Rs 48