From the graph, you can see that there are two lines, the red line which is for the expanses and the blue line which is for the income.
The fashion designer break even at a point where her income is equal to the expanses and this will be the point of intersection of both lines on the graph.
The point of intersection from the graph is at (100, 1250) that is;
x = 100
y = 1250
Since the number of hats are values that lies on the x axis, hence the fashion designer must sell 100 hats for her to break even