Write SQL query to solve given problem: How many purchases were made at Sac State American River Courtyard using Master Card?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(T1.TransactionID) FROM `transaction` AS T1 INNER JOIN location AS T2 ON T1.LocationID = T2.LocationID WHERE T2.LocationName = 'Sac State American River Courtyard' AND T1.CreditCardType = 'MasterCard'