The equation that would represent this situation is:
A = 2.5w + $12
To graph this you would substitute in varying numbers for w(the number of weeks) and this would be your x value in your ordered pair.
After you substitute in a number of weeks, you will get a total amount of money earned (A). This would be your y value in your ordered pair.
Here are some orders pairs you could plot to create the graph of this equation.
(1, 14.5)
(2, 17)
(3, 19.5)
(4, 22)