Answer: y = x
Step-by-step explanation:
Looking at the graph, we can retrieve two coordinates from the range we are given: (0, 0) and (5, 5). Because 1900 is the starting x-coordinate of the graph, we can represent it at 0.
You can find the slope of this equation using this formula:

Your slope is equal to 5/5, or 1.
Because the function's y-intercept is equal to 0, there is no need to add anything to the function.