Trfiangles ABC and ADE are similars, because they have to congruent angles: 90° and the common angle in vertex A, they theirs sides must be proportionals:
DE/AD=BC/AB
AD=AB+BD→AD=2+1→AD=3
Replacing the values:
x/3=1/2
Solving for x. Multiplying both sides of the equation by 3:
3(x/3)=3(1/2)
x=3/2
Answer: x=3/2