For random $w$ between $-20$ and $20$, what is the probability that the graphs of $x-\lfloor y\rfloor=w$ and $x^2+y^2=50$ meet in two points?

Question

From Mathcounts Nationals Target 2018:

6. Micaela randomly chooses a real number $w$ between -20 and 20. What is the probability that the graphs of $x-\lfloor y\rfloor = w$ and $x^2+y^2 =50$ intersect at exactly two points?

So, I know that the second equation is a circle with radius $5 \sqrt{2}$, but I don't know how to draw the graph for the first equation.