solve for x PLEASE and THANK YOU

Answer:
x = 5
Step-by-step explanation:
Because the sides shown are parallel, the triangles are similar. That means the lengths of their sides and segments of sides are proportional.
x/(x + 10) = 10/30
x/(x + 10) = 1/3
3x = x + 10
2x = 10
x = 5