Final answer:
The marked price of the printer is $600.
Step-by-step explanation:
To find the marked price of the printer, we need to first calculate the value before the GST was added. Let's represent the marked price as 'x'. We know that the printer was sold for $642 inclusive of 7% GST. To find 'x', we can set up the equation:
x + 0.07x = 642
Simplifying the equation, we have:
1.07x = 642
Dividing both sides by 1.07, we get:
x = 600
Therefore, the marked price of the printer is $600.