Robert is purchasing some equipment for his baseball team. He wants to buy some baseballs, each priced at m dollars. He has already spent b dollars on other equipment.

The following expression represents the total amount Robert will spend after buying x baseballs.



If the amount already spent by Robert on other equipment, b dollars, is doubled, then the value of m will ______________________.

If the cost of each baseball, m dollars, is tripled, then the value of b will_________________ and the value of mx will _______________________.