1. A steam iron consists on both heating plate and steam diffusing system that releasing hot steam while ironing clothes. Below are some technical specification of a steam iron (brand X), presented in Table 1. The steam iron consists two heating elements: one is for the heating plate, and other is for heating up steam in the water chamber, shown here in the diagram X. It can operate on either heating plate or steam diffusing system or in both systems simultaneouly Table 1. Specification of steam iron Specification Details specification Water tank capacity 1800 ml Continuous steam rate Max 120 g/min Power Max 2100 W Voltage 240 V Figure 1. Steam iron which works as hot plate and steam diffuser C. Suppose that both heating systems are operated simulataneously. How much energy is required to operate these systems within 30 minutes of ironing activity