let

x = the number of Wii game machines (in millions)

y = the number of PlayStation 3 consoles (in millions)

In 2007, Nintendo Co. sold three times as many Wii game machines in Japan as Sony Corp. sold PlayStation 3 consoles:

x = 3y

Together, they sold 4.84 million games machines in Japan:

x + y = 4.84

by solving the system of equations:

x = 3y

x + y = 4.84

we find:

x = 3.63 millions of Wii game machines

y = 1.21 millions of PlayStation 3 consoles

click here to see the step by step solution of the system of equations:

there were 3.63 millions of Wii game machines and 1.21 millions of PlayStation 3 consoles sold.