Find the value of x. Show all your work

Answer:
15
Step-by-step explanation:
Let the left side of the triangle be 2Y for the bigger triangle and then the smaller one will be Y.
Comparing the two triangle
2Y/Y = 30/X
2 = 30/X
Cross multiple
2X = 30
Dividing by 2
X = 30/2
X = 15