Answer:
x = 7 , MN = 19
Explanation:
a segment joining the midpoints of 2 sides of a triangle is
half the length of the third side
that is
MN =
JL , so
2x + 5 =
(8x - 18) ← distribute parenthesis by

2x + 5 = 4x - 9 ( subtract 4x from both sides )
- 2x + 5 = - 9 ( subtract 5 from both sides )
- 2x = - 14 ( divide both sides by - 2 )
x = 7
Then
MN = 2x + 5 = 2(7) + 5 = 14 + 5 = 19