Answer: k = 4
Step-by-step explanation:
Since x = 7 is the perpendicular bisector, then it is equal distance from both of the endpoints, which makes it the x-value of the midpoint.
[tex]\dfrac{X_A+X_B}{2}=X_{Midpoint}\\\\\dfrac{10+k}{2}=7\\\\10+k=14\\\\k=4[/tex]
