If segments AB and CD are congruent, then they have equal lengths:
5x-2=2x+7.
Solve this equation.
1. Separate terms with x and without x in different sides:
5x-2x=7+2,
3x=9.
2. Divide by 3:
x=3.
Then CD=2x+7=2·3+7=6+7=13.
Answer: correct choice is B.
