Answer:
8
Step-by-step explanation:
Use the pythagorean theorem. The hypotenuse (c) is 10, and one of the sides, let's say (b), is 6. Therefore, we need to solve for a and plug and chug. Let's do that:


Now let's plug in what we know:

Therefore, a = x = 8
If it’s only reflected over the y axis then only the x values change