Company A sends 4 L size boxes weighing Ikg and 5 M size boxes weighing 500g to Brunei using International Post which charges RM 330. Company B sends 7 size L boxes with the same weight and 10 M size boxes with also the same weight at RM 615. By assuming RM x is the cost to send the L size box and RM y is the cost for the M size box, find the value of x and y by using the matrix method.​