(3 marks) Chef Lemon worked at the restaurant, and he was trying a new cooling system that was claimed to be able to cool down his hot oven more quickly. The responsible technician told him that, under this new cooling system, the temperature inside the oven follows the equation dZM dM F _ 43E 42M, where M (t) denotes the temperature inside the oven in excess of the ambient temperature (which is 20C) 75 hours after the cooling system is turned on. This means the temperature inside the oven at time t is M (t) + 20 (C). Chef Lemon observed that, when he turned on the cooling system, M (0) = 300C and M " (0) : 200C per hour. According to the above equation, what would be the temperature inside the oven 30 minutes after the cooling system had been turned on (correct to nearest integer)