In the graph you can see two variables: Cost and Number of rooms to clean in house.
You can find the cost when both cleaning companies clean the same number of rooms as the point when the value in the varibles (y-axis and x- axis) are the same in the lines of both companies (the point where the lines cross each other)
Then, the cost when both companies clean the same number of rooms is $150 (the number of rooms to clean is 5 in both companies)