Fellow math lovers!

It's been quite sometime since I have solved basic probability problems. I am now trying to remember how to calculate geometric probability. As far as I remember, the general formula for a geometric probability calculation is (in my case):

$$\frac{P(X-Y\text{ segment})}{P(\Omega\text{ overall line segment})}$$

Could please someone give me a hand on how to solve the most basic geometric problem:

On the segment $[0, 1]$ two numbers $X$, $Y$ are being randomly selected. Find the probability that $X + Y \le 1$ and $X − Y > 0.1$.

Thank you in advance!