If both triangles are congruent (that's what the sign means), then AD=CB, and CD=AB. Substituting what we are given into CD=AB,
6x-5=3x+10
Solving the equation:
3x=15
x=5
So we know that 2x+4 (the value of AD) becomes 2*5 +4, and you get 14. Since we know that AD=CB, then CB is also 14. No need to find y!
Answer: CB=14
