You have to start with the left triangle and find the side lengths. Since it is a 45-45-90, both sides are the same. Rule for this is hyp= sqrt2 * leg
Since hyp = 6sqrt2, the leg is 6.
The leg is also the hypotenuse of the triangle on the right side.
x is the side across from the hypotenuse and it is the short leg so x = (1/2)6
x = 3
Answer:

Step-by-step explanation:
We know that 
Also , 
So ,

Answer:
x = 15
Step-by-step explanation:
3x / 3 = 45 / 3 x = 15