A knitting shop orders yarn from three suppliers in​ Toronto, Montreal, and Ottawa. One month the shop ordered a total of 108 units of yarn from these suppliers. The delivery costs were ​$78​, ​$53​, and ​$66 per unit for the orders from​ Toronto, Montreal, and​ Ottawa, respectively, with total delivery costs of ​$6826. The shop ordered the same amount from Toronto and Ottawa. How many units were ordered from each​ supplier?