In conjunction with the Olympic Games which was held in Tokyo, KOKUYO Company sold three types of souvenirs, that are keychains, calculators and pens. The company ordered its supply of souvenirs in two types of packets. The cost of a packet which consists of three keychains, and two calculators is RM45, whereas the cost of a packet which consists of a keychain, a calculator and a pen is RM40. The cost of a pen is four times the cost of a keychain. If the costs of a keychain, a calculator and a pen are RM x , RM y and RM z respectively, obtain a matrix equation to represent the above information. Hence, determine the cost of each type of souvenir supplied to the company.​