Answer:
12. BC = 8
14. JL = 18
Explanation:
You want to apply the Segment Addition theorem to two problems.
The segment addition theorem tells you the whole is the sum of the parts. The equation for each problem reflects this fact. When given values are substituted, the answer becomes clear.
12.
AB +BC = AC
7 +BC = 15
BC = 8 . . . . . . . . subtract 7
14.
JK +KL = JL
8 +10 = JL = 18
__
Additional comment
It often helps to draw a diagram.